Basic Almanac Data

• 30-year Averages from the National Climatic Data Center (NCDC)
• Averages and Records for Oklahoma City and Lawton, OK and Wichita Falls, TX.
• Monthly Summaries (F6 reports)
• Yearly Climate Graphs can be found at the NOWData web page.

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Climate Products

Product	Abbr.	Product	Abbr.
Daily Climate Summary		Monthly Climate Summary
Oklahoma City	CLIOKC	Oklahoma City	CLMOKC
Wichita Falls	CLISPS	Wichita Falls	CLMSPS
Lawton	CLILAW	Lawton	CLMLAW
Record Event Report		Other Products (Issued as needed.)
Oklahoma City	REROKC	Supp. Temp/Precipitation Table	AGO
Wichita Falls	RERSPS	Daily Precipitation Report	RRM
Lawton	RERLAW	Public Information Statement	PNS
Regional Temperature and Precipitation Table
Oklahoma	RTPOK
Texas	RTPTX

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Links to Climate Websites

U.S. Government Climate Centers

• National Centers for Environmental Information (NCEI)
• National Drought Mitigation Center (NDMC)
• Climate Prediction Center

State Climate Agencies

• Oklahoma Climatological Survey
• Texas State Climatologist

Regional Climate Centers

• Midwestern Regional Climate Center
• High Plains Regional Climate Center
• Northeast Regional Climate Center
• Southern Regional Climate Center
• Southeastern Regional Climate Center
• Western Regional Climate Center

Other Links

• U.S. Naval Observatory Sunrise, Sunset, and Moon Phase Information
• Extreme Rainfall and Rainfall Frequency Estimates
• Weekly Weather and Crop Bulletin

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Significant Weather

• Heavy Snow


• Drought


• Heat Wave Information for:
  • Oklahoma City, OK
  • Wichita Falls, TX
• Heat Bursts

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Heavy Snow in Oklahoma - Where, When, and How Often?

Introduction

Note: The following information is based on a long-term snowfall study conducted by WFO Norman staff. The study was used to write a technical memorandum entitled "Monthly and Geographic Distribution of Heavy Snow Events in Oklahoma, 1951-2001." within the Special Topics tab.

After sifting through more than 50 years of daily snowfall reports in Oklahoma, forecasters at WFO Norman have identified 225 heavy snow events that occurred within the Sooner State between January 1951 and April 2001. "Heavy" snow events are defined here as those which produced at least one 24-hour snowfall report of 6 inches or more, or at least two 24-hour snowfall reports of 4 inches or more. (Note that there may have been additional events that were not reported. Heavy snow sometimes falls in very localized areas, in which case the heaviest amount may not fall at a reporting station.)

For the entire state, the average number of events per season is somewhere between 4 and 5. But the range is from none at all (in 1962-63 and 1974-75) to a maximum of 11 (1972-73).

The 225 events were sorted by calendar month to produce a graph of the relative monthly distribution of Oklahoma heavy snow events. Heavy snow has fallen in the state as early as the second week of October (8-9 October 1970) and as late as the first week of May (3 May 1978). The frequency increases gradually from October through December, to a peak in January. But from there the frequency levels off through February and March, before falling sharply in April. An interesting note is that "major" snowstorms, producing maximum storm totals of 16 inches or more, show a marked preference for March. In fact, five of the top ten snowstorms (based on maximum reported storm totals) in Oklahoma since 1951 occurred in March. These storms are listed in the following table.

Each of the 225 events was mapped by plotting all available storm-total snowfall amounts, and highlighting the counties which were affected - wholly or in large part - by snowfall of 4 inches or more. An example can be seen here, which shows the distribution of snowfall during the major winter storm of late December 2000. (Note: This event will be remembered most for the crippling ice storm across much of southern and eastern Oklahoma. But the map only shows snowfall, not ice accumulation.)

Once we identify and map each event, the same way we did for the late-December 2000 event, we can obtain the total number of events in each county, by month and by season, over the entire 51-plus year period. The results will give us a reasonably good idea of things like: How often we can expect heavy snowfall, what month (or months) it is most likely to fall in, and how the frequencies vary across different parts of the state.

The total number of events in each county shows that most Oklahoma heavy snowstorms affect the panhandle and northwest. Counties along the Red River in south central and southeast Oklahoma received the fewest events, but even in these counties there were more than a dozen events over the 51-year period. The numbers can be divided by the period of record (51 years) to obtain an estimate of the annual frequency of heavy snow events in a given county. For example, the numbers for Oklahoma and Tulsa counties are 38 and 44 respectively, which when divided by 51 yield numbers which are less than 1 but greater than 0.5. This translates into an average frequency of less than one event every year, but more than one every two years. Thus, heavy snow events occur in both the Oklahoma City and Tulsa areas roughly once every 1 to 2 years. For the panhandle and most of northwest Oklahoma, the frequencies are higher, averaging something between 1 and 2 heavy snow events per year. This is more than 5 times higher than the frequency in the counties in far southeast Oklahoma, where heavy snow occurs on average about once every 3 to 4 years.

We also looked at the county-by-county frequency of storms which produced maximum snowfall totals of 8 inches or more. The county totals for 8-inch events show a similar distribution to that of 4-inch events, except that the numbers are, of course, much lower (8-inch events are far less frequent). The numbers suggest that 8-inch snowstorms affect the panhandle counties about once every 1 to 2 years on average, but that the Red-River counties average only one such event every 20 years or so.

The monthly frequency of heavy snow varies across different parts of the state. To look at this variation, we divided the state into 17 regions and calculated the average number of events by month in each region. This resulted in 17 monthly-distribution graphs, each similar to the one seen earlier for the entire state. (We left May off of these graphs, since there was only one May event and it was confined to the western panhandle.) Comparison of the graphs shows that January is the peak month across most of southern and east-central Oklahoma, but February is the peak month across most of west-central and north-central Oklahoma. In between, peak frequencies generally are split between January and February across much of southwest, central, and northeast Oklahoma (including the Lawton, Oklahoma City, and Tulsa areas). In far northwest Oklahoma, including the panhandle, the peak month is March. But there are slight indications of two peaks, with an earlier peak suggested in December or January, followed by a relative minimum in January or February. This suggests that heavy snow may be more likely either early or late in the cold season than it is in mid-winter in far northwest Oklahoma.

The double peak also shows up in the distribution of 8-inch events (darker bars in the 17 regional graphs ) across northwest Oklahoma, and also appears in northeast Oklahoma. In fact, March emerges in northeast Oklahoma as the most likely month for 8-inch snowfalls.

Summary:

• The probability of heavy snow in Oklahoma increases gradually through fall and early winter to a peak in January, then remains high through March before dropping sharply in April.


• The panhandle and northwest counties are the most likely areas to receive heavy snow, averaging one to two 4-inch or greater snow events per year, and one 8-inch event every 1 to 2 years.


• Counties along the Red River in southern Oklahoma are least likely to experience heavy snowfall, but still can expect one 4-inch or greater snowfall on average every 3 to 4 years. Snowfalls of 8 inches or more occur on average in these areas only about once every two decades.


• The three largest population centers in Oklahoma - Oklahoma City, Tulsa, and Lawton - all average one 4-inch or greater snowfall event every 1 to 2 years. Eight 8-inch or greater events average roughly one every 5 years in Tulsa, one every 5 to 10 years in Oklahoma City, and one every 10 to 20 years in Lawton.


• The peak month for 4-inch or greater events varies from January across southern and east central Oklahoma, to February in west-central and north-central Oklahoma, to March in the panhandle and far northwest. There may be a secondary early-season peak (December or January) in the far northwest.


• Peak months for 8-inch or greater events are generally the same as those for 4-inch events - except in northeast Oklahoma, where the 8-inch peak shifts to March.


• The most likely place and time to experience heavy snow in Oklahoma: The Panhandle in March.

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Heat Wave and Summer Temperature Data for Oklahoma City, Oklahoma

How does the current or a recent summer compare to other years with hot summers such as 1934, 1936, 1943, 1954, 1980, 2000, 2006, 2011, and 2012 for Oklahoma City? Please review the data tables below. Heat wave information for Wichita Falls, TX is available here.

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Heat Wave and Summer Temperature Data for Wichita Falls, Texas

How does the current or a recent summer compare to other years with hot summers such as 1934, 1936, 1943, 1954, 1980, 2000, 2006, 2011, and 2012 for Wichita Falls? Please review the data tables below. Heat wave information for Oklahoma City, OK is available here.

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All About Heat Bursts

A heat burst is a meteorological phenomenon in which air descending from a decaying thunderstorm causes a rapid temperature increase and strong straight-line winds at the surface. This page explains how heat bursts form, shows radar and mesonet observations from a recent event, and answers some common questions about heat bursts.

How Heat Bursts Work    |    An Example: June 9, 2011, Enid, OK     |    Common Heat Burst Questions

How Heat Bursts Work

A Dying Storm

A heat burst typically begins with a dying thunderstorm, which often takes on a “serpentine” shape on radar (see image). As in many decaying thunderstorms, air high in the storm is cooled by evaporation of some of the water in it (just as evaporation of sweat cools your skin). As the air cools, it becomes denser than the air around it and begins to sink.

“Serpentine” radar echo from May 23, 1996 heat burst

It Begins Like a Downburst…

Normally, sinking air will be compressed by the weight of the air above it and will warm as it sinks. In a dying thunderstorm, however, the cooling of the air by evaporation offsets the warming caused by compression. End result: As long as there is still evaporation going on, the air inside the thunderstorm stays cooler than the air around it and keeps on sinking.

If the air around the thunderstorm is very dry, then rapid evaporation can cause large amounts of cooling, causing the air inside the storm to sink at very high speed. A downburst, characterized by strong winds and cool, moist air, occurs when this rapidly sinking air hits the ground while evaporational cooling is still occurring (i.e. while it still contains liquid water).

A Trick Up Nature’s Sleeve

In a heat burst, all of the water in the sinking air is evaporated before it reaches the ground. At this point, the air begins to warm due to compression without any evaporation to counter it. This warming slows the descent of the downdraft. However, if it has sufficient momentum built up, the hot, bone-dry air will still push its way down to the surface, hitting and spreading out as a sudden burst of hot, gusty wind.

An Example: June 9, 2011 near Enid, OK

Below are some images from a heat burst event that occurred in late spring 2011 near Enid, OK.

These graphs show the air temperature, relative humidity, and maximum wind gusts in Breckenridge, OK from 10 PM to 1 AM. The heat burst caused a 15 degree temperature increase and a 31% drop in relative humidity in 20 minutes. At the same time that the temperature was spiking, wind gusts reached 50 mph.

Common Heat Burst Questions

When do heat bursts typically occur in our area?

Most heat bursts happen at night or during the early morning, when surface temperatures are cooler. The most common times of year for a heat burst to occur are late spring and summer. During those seasons, we frequently see strong thunderstorms move into our area and die off overnight – a sequence of events that sets the stage for heat bursts.

How strong are heat bursts?

Just as “rain” encompasses everything from light sprinkles to a heavy downpour, heat bursts vary in intensity from very weak to very strong. Heat bursts that produce 10 ° F temperature increases and 50-plus mph winds are not uncommon.

On May 22, 1996, one of the strongest heat bursts ever recorded in our area occurred between Lawton and Chickasha, OK. Temperatures in Chickasha increased from 87 to 102 degrees, and winds in Tipton, OK gusted to 105 mph. The Lawton area alone suffered $15 million in damage from the straight-line winds produced by the event.

How common are heat bursts?

Once thought to be fairly rare, dense observation networks such as the Oklahoma Mesonet have shown that, while they are strange, heat bursts are actually fairly common in late spring and summer in Oklahoma and Western North Texas. An Oklahoma Climatological Survey study found that more than a dozen heat bursts typically occur every year in Oklahoma alone.

How does a heat burst compare to a downburst?

You are probably familiar with downbursts- strong wind events caused by cold, wet air flowing out of a thunderstorm. Downbursts and heat bursts have some similar characteristics. In fact, both typically begin in exactly the same way – with cold, moist air sinking inside a thunderstorm. However, by the time they reach the surface, they are very different events.

Similarities:

• Both are caused by thunderstorms.
• Both involve downward-rushing air hitting the surface and spreading out.
• Both originate as an area of cool, moist air falling downward through a thunderstorm.
• Both can cause damaging winds at the surface.

Differences:

• When downbursts reach the surface, they contain cool, moist air, frequently with rain or even hail.
• When heat bursts reach the surface, they contain hot, dry air.

What ingredients are necessary for a heat burst?

These are the basic ingredients of a heat burst. Even with all of these ingredients, a heat burst will not occur unless the local environment is just right.

• Time: Late night or early morning
• Decaying thunderstorm
• Deep layer of very dry air aloft
• Low level inversion (temperatures at the surface are cooler than just above the surface)

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Special Topics

• The Seasons


• La Nina's Influence on Winter Season


• Monthly and Geographic Distribution of Heavy Snow Events in Oklahoma, 1951-2001


• Summertime Temperature Facts for:
  • Oklahoma City, OK
  • Wichita Falls, TX

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The Seasons - Oklahoma and Western North Texas

Thanks to the tilt of the Earth at ~23.5°, we get to experience 4 seasons. Some of the seasons seem longer than others (think summer) over Oklahoma and western north Texas, but we have 4 pretty distinct seasons. The types of weather we experience usually revolve on the amount of sunshine that is received. For several months of the year,the northern hemisphere receives more direct rays of the sun (June through September) than the other half (December through March). The other four months are our "transition" months. Below is what we can expect with the changing seasons.

What is happening at the beginning of each season?

Spring (Vernal) Equinox

Around March 21 (or between March 20-22), the sun passes directly over the equator. Almost equal amounts of sunshine occur over all areas. Those of us north of the Equator are getting ready for warmer weather, while those to the south are looking for the winter jackets. The sun's more direct warming rays are crossing from the southern hemisphere to the north. These rays of sunshine will help get the grass growing again (or at least accelerate it) and the plants blooming. In Oklahoma, it is our wet season, but also spans much of the severe weather season.

Summer Solstice

Around June 21 (or between June 20-22) is the first of two equinoxes, or the beginning of summer. Ahh, the day with most amount of sunshine, but also the start of what is usually some very, very hot weather over Oklahoma and western north Texas. On this day, the sun reaches its furthest north point in the sky, and slowly begins to set further and further south. But the rays of sunshine are hitting us in full force, which usually leads to temperatures in the 90s to over 100 degrees at times.

Fall (Autumnal) Equinox

Around September 21 (or between September 20-23) marks the second equinox of the year. The sun is crossing the equator, going from the northern Hemisphere into the southern Hemisphere. All areas of the Earth will receive approximately the same amount of the sun's rays. Normally a welcome time of the year, as summers over Oklahoma and western north Texas are usually quite hot. The northern hemisphere begins to tilt away from the sun's direct energy, which finally should begin to cool us off. The north pole (think Santa) will point further and further from the sun, which means shorter daylight hours, and in some cases (Alaska), the daylight hours diminish faster and faster.

Winter Solstice

Around December 21 (or between December 20-22), we experience our second solstice of the year. Even with the proximity of the Earth to the Sun being at its closest point, the northern hemisphere is facing away from the sun, which means a prolonged period of cooler (or colder) weather. The first day of winter also has the fewest amount of daylight hours. However, the number of daylight hours slowly increases as we get closer to Spring.

Shown below is an image showing the placement of the Earth at the beginning of each season. The dates shown are approximate.

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La Nina's Influence on the Winter Season in Oklahoma

La Niña is the term used to describe cooler-than-average sea surface temperatures across the eastern two-thirds of the tropical Pacific. The more familiar El Niño, refers to warmer than average conditions. Both La Niña and El Niño influence global weather patterns, bringing floods to some and drought to other regions.

Since the early 1950s, twenty cold episodes (La Niña) have been observed during the winter months (December – February). Temperature and precipitation data from 5 climate divisions (OK02, OK04, OK05, OK07 & OK08 cover most of the NWS Norman forecast area) were analyzed to see how La Niña influences the weather across parts of Oklahoma.

Monthly temperatures averaged near normal to above average for practically every event during the month of December, especially the two southern climate divisions. Monthly temperatures for January and February were more fickle, especially February, when very warm and very cold temperatures are more likely to occur.

Precipitation data were ambiguous. However, many of the early episodes (1950-mid 1970s) were generally dry or below average with recent years near normal to above normal, especially during the month of December.

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Winter Season Precipitation and Temperature Trends for Oklahoma Climate Division 2

December Precipitation Trend	January Precipitation Trend	February Precipitation Trend
December Temperature Trend	January Temperature Trend	February Temperature Trend

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Winter Season Precipitation and Temperature Trends for Oklahoma Climate Division 4

December Precipitation Trend	January Precipitation Trend	February Precipitation Trend
December Temperature Trend	January Temperature Trend	February Temperature Trend

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Winter Season Precipitation and Temperature Trends for Oklahoma Climate Division 5

December Precipitation Trend	January Precipitation Trend	February Precipitation Trend
December Temperature Trend	January Temperature Trend	February Temperature Trend

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Winter Season Precipitation and Temperature Trends for Oklahoma Climate Division 7

December Precipitation Trend	January Precipitation Trend	February Precipitation Trend
December Temperature Trend	January Temperature Trend	February Temperature Trend

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Winter Season Precipitation and Temperature Trends for Oklahoma Climate Division 8

December Precipitation Trend	January Precipitation Trend	February Precipitation Trend
December Temperature Trend	January Temperature Trend	February Temperature Trend

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Monthly and Geographic Distribution of Heavy Snow Events in Oklahoma, 1951-2001

Introduction

Heavy snowfall events are rare in Oklahoma relative to other parts of the United States, but they occur with sufficient frequency to create a significant forecasting challenge. The purpose of this study is to quantify the frequency of heavy snow events in Oklahoma, in terms of monthly and seasonal trends as well as geographic distribution within the state.

Methodology

Monthly climatological data summaries, compiled by the National Climatic Data Center, include daily 24-h snowfall totals from available first-order and cooperative observer stations in Oklahoma. Summaries typically include daily reports from 100 or more stations. The actual number varies from month to month, due to missing or incomplete data, relocation of observing sites, and/or changes in active status of some sites over the years.

Heavy snow events, for purposes of this study, are defined as those which produce at least one observed 24-h total of six inches or more in the state, or at least two observed 24-h totals of four inches or more. Once either of these criteria were met, snowfall totals were examined for every available observing site from that date and the dates immediately preceding and following it. Storm totals were determined at each site by adding all measurable snowfall totals on consecutive days including and surrounding the date identified. Each event was identified using the first and last calendar dates in which measurable snowfall was reported, e.g., 5-7 January 1988. (Note that some events did not occur entirely within a single calendar month, e.g., 31-December 2000-1 January 2001. Such events were assigned to either a] the month with the most calendar days affected, or b] the month in which they began. So the above example was a December event, while one occurring over, say, 31 January - 2 February would be a February event. Surprisingly, there were very few such "end-of month" events.)

Geographic distribution of snowfall for each event was determined by identifying the counties which were wholly or largely affected by storm totals of four inches or more and eight inches or more. A certain amount of subjectivity was necessary, due to variations in the number and distribution of available reports. For each event, there were enough data points to develop a reasonably accurate subjective analysis of geographic snowfall distribution for that event. But there were very few data points for which data were available consistently throughout the entire 50-year period of study. Many sites either closed, opened, relocated, or had missing reports at some point during the period. As such, it was not possible to develop long-term objective numbers of events for each specific observing site.

All available storm totals were plotted and subjectively analyzed for each event, providing a map of the geographic distribution of snowfall for that event. Counties affected by the event were then identified based on the analysis. An example is shown in Fig. 1. Note that in many cases there were counties which did not contain any data points, so it became necessary to evaluate the analyses to determine whether those data-void counties were affected by the event. (The process of determining counties affected is qualitatively similar to determining which counties are to be included in a severe thunderstorm or tornado watch. The process arguably is subjective in many cases, but should yield meaningful data given a sample size of over 200 events.) Seasonal and monthly frequencies of events for each county were then determined by simply adding up the total number of events affecting the given county.

Monthly and Seasonal Distribution

A total of 225 heavy snow events were identified between January 1951 and April 2001, a period of just over 51 years. This results in an average of between four and five events per season. There have been only two winter seasons without a heavy snow event in Oklahoma: 1962-63 and 1973-74. In other words, heavy snow has fallen somewhere in Oklahoma in roughly 95 percent of all winter seasons. Of the 225 events which produced storm totals of four inches or more, 189 produced these amounts somewhere in the main body of Oklahoma; heavy snowfall in the remaining 36 events was confined to the three counties of the Oklahoma panhandle.

Heavy snow events have occurred as early as October and as late as May. The earliest event occurred on 8-9 October 1970, while the latest occurred on 3 May 1978. (Both were limited to the far western panhandle.) The overall frequency of events increases gradually to a peak in January, then remains relatively constant through February and March, before dropping much more abruptly in April (Fig. 2).

Of the 225 events, 102 produced maximum totals of 8 inches or more (two per year), 48 produced a foot or more somewhere (nearly one per year), and 14 produced a maximum storm total of 16 inches or more (about once every three years). The monthly distribution of eight- and 12-inch events (Fig. 2) shows a relatively constant frequency throughout the peak months of December through March. But the distribution of 16-inch events shows an interesting late-season peak, with a maximum in March. This apparent preponderance of "mega" snowstorms late in the winter season is further demonstrated in the list of ten heaviest snowstorms in Table 1 (as ranked by maximum storm total): Five of the ten heaviest events occurred in March.

Table 1. Heaviest snowfall events in Oklahoma, 1951-2001. Rankings are based on maximum storm totals (Max, inches). Location of the maximum reported storm total for each event is given.

Geographic Distribution

The numbers in Fig. 3 were obtained for each county by tallying the number of times the given county was "hit" by heavy snowfall during the period. They thus represent the number of heavy snow events which produced four-inch or greater storm totals over at least a part of the county. With the period of study being just over 51 years, one can divide the numbers shown by 51 to obtain an approximate annual (or seasonal) frequency of four-inch or greater events. These frequencies are depicted by contours representing "turnaround times," i.e., the average time between four-inch snowfall events in the given area.

(Note: It is reasonable to expect that larger counties would have more events than smaller ones, simply by virtue of the fact that they are larger "targets." However, the data do not show a distinct size bias in most cases, probably because the counties of Oklahoma are, for the most part, similar in size. One exception was made for Osage county in northeast Oklahoma, which is noticeably larger than surrounding counties. In order to minimize any potential size bias, Osage county was split into north and south sections for this study. The dividing line is an eastward extension of the border between Kay and Noble counties, the two counties immediately west of Osage county.)

Figure 3 shows a marked preference for heavy snow in northwest Oklahoma. Much of the northwest one-fourth of the state experiences heavy snow more than once per year, on average. In the western and central panhandle, the average is closer to two per year. These frequencies are more than five times greater than those along the Red River counties in far south central and southeast Oklahoma, where heavy snow falls on average only about once every three to four years. For much of the rest of Oklahoma, including the larger population centers around Lawton, Oklahoma City, and Tulsa, heavy snow events occur, on average, once every one to two years.

Figure 4, obtained in the same manner as Fig. 3, shows the frequency of eight-inch or greater snowfall events. Geographic distribution generally is similar, with greatest frequencies in the panhandle and northwest. Snow events of eight inches or more occur on average more than once every other year in the panhandle. Lowest frequencies extend along the entire Red River region, where the data suggest eight-inch snowfall events occur on average only once every 20 years or so. Most of the counties in west central, central, and northeast Oklahoma average around 5 to 10 years between eight-inch snowfall events.

In order to look at geographic variations by month, the numbers in Figs. 3 and 4 were broken down by month. (Actually, the monthly totals were derived first; Figs. 3 and 4 were obtained later by adding up the respective monthly totals.) The monthly results constituted another eight pairs of figures similar to Figs. 3-4. In the interest of condensing the presentation of all these data into a more manageable form, it was decided to divide the state into a number of regions, and calculate monthly numbers for each region by averaging the monthly totals from each of the counties in that region. These numbers then could be plotted in the form of bar graphs for each region, and displayed on a single figure which would show frequency variations by month and by region. The result is shown in Fig. 5.

Subdivision of the state began with the nine standard geographic divisions used by the Oklahoma Climatological Survey (OCS) in their data publications. A further subdivision was performed by splitting eight of the divisions in half again (all but the southeast division). The final result is 17 subdivisions as shown in Fig. 5, with solid lines outlining the OCS regions and dashed lines indicating the subdivisions.

Looking at the distribution of four-inch or greater events (light gray bars on the graphs in Fig. 5), it is clear that January is the peak month across southern and east central Oklahoma. But the peak month shifts to February from west central to north central Oklahoma. In between, much of southwest, central, and northeast Oklahoma is equally split between January and February. In the panhandle and far northwest, the peak month is March. In fact, the highest frequencies for any month and any region are in the panhandle region in March. But there is evidence of a bi-modal distribution in the far northwest, which includes a secondary earlier peak in December or January.

Evidence for a dual peak in frequencies in far northwest Oklahoma is more evident in the distribution of eight-inch events (darker bars in Fig. 5). A relative minimum in January or February is present in the three northwestern-most regions, and in fact extends eastward into northeastern Oklahoma. In general, frequency distributions for eight-inch events are consistent with those for four-inch events. But the data show that in northeastern Oklahoma, the peak time for eight-inch snow events shifts from January/February to March. These findings are consistent with the fact that a larger number of "big" snow events occur later in the season (section 3 and Table 1).

Summary

Oklahoma averages between four and five heavy snow events per season. They are most likely to occur in northwest Oklahoma, where most counties can expect one to two snowfalls of four inches or more per season. Far south-central and southeast Oklahoma are the least likely areas to receive heavy snow, but even these areas can expect a four-inch or greater snowfall about once every three to four years. On a seasonal basis, heavy snow can occur in the state as early as October or as late as early May (at least in the panhandle).

For the state as a whole, the frequency of heavy snow events increases gradually through fall and early winter to a peak in January, then levels off through February and March before dropping sharply in April. But the peak frequency varies by region - January in southern and east-central Oklahoma, to February in west central and north-central Oklahoma, to March in the panhandle. The most likely time and place for a heavy snow event in the state is in the panhandle in March. The panhandle area may experience a dual peak in heavy snow frequency, with the maximum in March preceded by a weaker maximum in December or January and a relative minimum in January or February.

The monthly frequency of "big" snow events, which produce eight inches or more, generally is similar to that of four-inch events - except in northeast Oklahoma, where the peak frequency shifts to March. Data on even larger "mega-snow" events, producing storm totals of 16 inches or more, suggest that March is the most likely month of occurrence in Oklahoma.

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Summertime Temperature Facts for Oklahoma City, Oklahoma

Facts and Tidbits

• Average First 90° Temperature - ~May 6
• Earliest 90° Temperature - February 1, 1911 (90°)
• Average Last 90° Temperature - ~September 27th
• Latest 90° Temperature - October 26, 1891 (92°)
• Average First 100° Temperature - ~July 10th
• Earliest 100° Temperature  - April 12, 1972 (100°)
• Average Last 100° Temperature - ~August 20th
• Latest 100° Temperature - September 30, 1977 (100°)
• Hottest Temperature on Record - 113° (August 11, 1936 and August 3, 2012). In 1936, the high temperature was 112° on August 10th and 110° on August 12th. In 2012, the high temperature was 112° on August 1st and 2nd.
• Warmest Low Temperature on Record - 84° (August 3, 2012)
• Average Temperature for the Hottest Climatological Summer (June thru August) - 87.4 (2011). The previous record was 85.9° (1980).
• Average Temperature for the Hottest June - 85.4° (1953)
• Average Temperature for the Hottest July - 89.2° (2011). The average high temperature was 102.5°.
• Average Temperature for the Hottest August - 89.0 (2011) The previous record was 88.7° (1936).
• Average Temperature for the Hottest September - 82.2° (1931)
• Hottest June Temperature on Record - 107° (June 22, 1936)
• Hottest July Temperature on Record - 110° (July 6, 1996 & July 9, 2011)
• Hottest August Temperature on Record - 113° (August 11, 1936 and August 3, 2012)
• Hottest September Temperature on Record - 108° (September 2 & September 3, 2000)

High Temperatures ≥ 110°:

• August 10, 1936 - 112°
• August 11, 1936 - 113°
• August 12, 1936 - 110°
• August 2, 1980 - 110°
• July 6, 1996 - 110°
• July 9, 2011 - 110°
• August 5, 2011 - 110°
• August 6, 2011 - 110°
• August 1, 2012 - 112°
• August 2, 2012 - 112°
• August 3, 2012 - 113°

Notable 90° & 100° Streaks:

• Most Consecutive 100°+ Days - 22 (August 4 - 26, 1936). The most recent streak was 18 consecutive days ending on August 4, 2012 (3rd longest).
• Most Consecutive Days With Temperatures ≥ 105° - 7 (July 31-August 6, 2011 and July 29-August 4, 2012)
• Most Consecutive Days With Temperatures ≥ 110° - 3 (August 10-August 12, 1936 and August 1-3, 2012)
• Most Consecutive 90°+ Days - 71 (June 23 - September 1, 1980 and June 1 - August 10, 2011).
• Fewest 100°+ Temperatures in a Calendar Year - 0 (Numerous times, most recently in 2021)
• Most 100°+ Temperatures in a Calendar Year - 63 (2011) The previous record was 50 (1980).
• Most 100°+ Temperatures in June - 12 (1953)
• Most 100°+ Temperatures in July - 27 (2011)
• Most 100°+ Temperatures in August - 24 (2000)
• Most 100°+ Temperatures in September - 7 (2000)
• Highest Number of Days With Temperatures ≥ 90° in a Calendar Year - 113 (1998)
• Highest Number of Days With Temperatures ≥ 90° in June - 30 (2011)
• Highest Number of Days With Temperatures ≥ 90° in July - 31 (1954, 1980, 2003, 2006, 2011 & 2012)
• Highest Number of Days With Temperatures ≥ 90° in August - 31 (1938, 1980, 1999 & 2000)
• Highest Number of Days With Temperatures ≥ 90° in September - 25 (1939)

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Summertime Temperature Facts for Wichita Falls, Texas

Facts and Tidbits:

• Average First 90-Degree Temperature - ~April 9
• Earliest 90-Degree Temperature - February 11, 2017 (94°)
• Average Last 90-Degree Temperature - ~October 11
• Latest 90-Degree Temperature - November 11, 2017 (90°)
• Average First 100-Degree Temperature - ~June 10
• Earliest 100-Degree Temperature - March 27, 1971 (100°)
• Average Last 100-Degree Temperature - ~September 6
• Latest 100-Degree Temperature - October 17, 1972 (102°)
• Hottest Temperature on Record - 117° (June 28, 1980). The temperature was 116° the day before.
• Warmest Low Temperature on Record - 88° (July 26, 2011). The previous record warm low temperature was 87° on August 16, 1952 which was also achieved on August 3, 2011.
• Average Temperature for the Hottest Climatological Summer; (June thru August) - 91.9° (2011). The previous record was 88.5° (1980).
• Average Temperature for the Hottest June - 89.5° (2011)
• Average Temperature for the Hottest July - 92.9° (2011)
• Average Temperature for the Hottest August - 93.4° (2011). The previous record was 91.1° (1952).
• Average Temperature for the Hottest September - 84.9° (1931)
• Hottest June Temperature on Record - 117° (June 28, 1980)
• Hottest July Temperature on Record - 114° (July 15, 1978, July 2, 1980, & July 3, 1980)
• Hottest August Temperature on Record - 113° (August 11, 1936 & August 6, 1964)
• Hottest September Temperature on Record - 111° (September 4, 2000)

High Temperatures ≥ 112°:

• August 11, 1936 - 113°
• August 3, 1943 - 112°
• August 6, 1964 - 113°
• August 13, 1969 - 112°
• August 9, 1970 - 112°
• July 15, 1978 - 114°
• June 24, 1980 - 112°
• June 25, 1980 - 114°
• June 26, 1980 - 113°
• June 27, 1980 - 116°
• June 28, 1980 - 117°
• June 29, 1980 - 112°
• July 1, 1980 - 113°
• July 2, 1980 - 114°
• July 3, 1980 - 114°
• June 27, 1994 - 113°
• August 1, 2012 - 112°
• August 2, 2012 - 112°
• July 19, 2018 - 112°
• July 20, 2018 - 112°
• July 22, 2018 - 112°

Notable 90° & 100° Streaks:

• Most 100-Degree Temperatures in a Calendar Year - 100 (2011). The previous record was 79 (1980).
• Fewest 100-Degree Temperatures in a Calendar Year - 1 (1950)
• Most Consecutive Days With Temperatures ≥ 100° - 52 (June 22 - August 12 2011). The previous record was 42 (June 23 - August 3, 1980). In 1980, the temperature reached 117°, 116°, 114° (3 times), 113° (2 times), and 112° (2 times) during the streak.
• Most Consecutive Days With Temperatures ≥ 90° - 100 (May 27 - September 3, 2011). The previous record was 98 (June 11-September 16, 1980).
• Most Consecutive Days With Temperatures ≥ 105° - 26 (June 24-July 19, 1980)
• Most Consecutive Days With Temperatures ≥ 110° - 10 (June 24-July 3, 1980)
• Most 100-Degree Temperatures in June - 28 (2011). The previous record was 20 (1953)
• Most 100-Degree Temperatures in July - 31 (1980, 2011)
• Most 100-Degree Temperatures in August - 30 (2000)
• Most 100-Degree Temperatures in September - 10 (1938, 1939, 2000)
• Most 100-Degree Temperatures in October - 2 (1938, 1951, 1979, 2000)
• Highest Total of Temperatures at least 90-Degree in a Calendar Year - 142 (1963)
• Highest Total of Temperatures at least 90-Degree in June - 30 (1925, 1934, 1984, 2011)
• Highest Total of Temperatures at least 90-Degree in July - 31 (numerous, most recently 2018)
• Highest Total of Temperatures at least 90-Degree in August - 31 (numerous, most recently in 2011)
• Highest Total of Temperatures at least 90-Degree in September - 28 (1933)
• Highest Total of Temperatures at least 90-Degree in October - 16 (1933 & 1963)

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Holiday Facts

• Christmas (Oklahoma City)
• Christmas (Wichita Falls)
• Probability of a White Christmas

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NWS Weather Facts for Christmas Day at Oklahoma City, Oklahoma

The following are some numbers related to Christmas Day weather in Oklahoma City, Oklahoma. The numbers are based on records going back to 1890.

Some of the more memorable weather events on Christmas Day in recent years include... 1955: The high of 54 was above average, but was a 32-degree drop-off from the previous day. A high of 86 on Christmas Eve was 38 degrees above the long-term average, and still stands as the all-time record high temperature for December. 1975: Rain changed to snow on Christmas Eve, with heavy snow falling that afternoon and continuing into early Christmas morning. Nearly 3 inches fell during the storm, but temperatures hovered just above freezing, and much of the snow melted when it reached the ground. 1983: Bitter cold with wind chills as low as 27 below occurred during the pre-dawn hours of Christmas Day. The high of 13 was an improvement over the previous day, as the high on Christmas Eve was 3 above zero. The low was zero, and wind chills dropped as low as minus 45 as north winds gusted to 38 mph. 1987: Freezing rain and sleet began before sunrise, and was the start of an infamous 2-day ice storm that left parts of Oklahoma without power for over a week. Sleet prevailed across the western and northern parts of Oklahoma City, while freezing rain devastated southern and eastern parts of the metro area. Despite heavy sleet and ice accumulations of up to 2 inches, total snowfall was only a trace. 1989: Christmas Day was a sunny, mild day with temperatures in the 50s. But what made this Christmas memorable was the dramatic warm-up that was in progress. Three days earlier the temperature fell to minus 4, a new all-time record low for December. Winds of 20 mph at the time dropped wind chills to near 50 below. The next night, the December low temperature record was broken again when the temperature fell to minus 8. Two days later on Christmas Day, the temperature reached 57, giving Oklahoma City a 65-degree warm-up in two days. 2000: A major winter storm affected much of Oklahoma on December 25-26, with impacts similar to the storm in 1987. The storm began on Christmas Day across the region, with significant accumulations of snow and ice occurring Christmas night and into December 26. Heavy snow, accumulating 8 to 12 inches, fell across northwest Oklahoma. Meanwhile, a combination of snow, sleet, and freezing rain fell across west-central, central and north-central Oklahoma, with accumulations ranging from 2 to as much as 8 inches. One of the worst ice storms to ever affect the state of Oklahoma occurred in south-central and southeast Oklahoma, where ice and sleet accumulations from 1 to 2 inches were common. Statewide, around 170,000 residents were without electricity right after the storm, and power was not restored in some locations until almost 2 weeks later. 2009: Although no snow technically fell on Christmas Day, the record-setting blizzard that affected a large part of Oklahoma on Christmas Eve was fresh on everyone's mind. Snow accumulated between 5 and 7 inches from southwest into central Oklahoma, with several locations reporting over 10 inches! The snowstorm was made worse by the near continuous winds that were sustained near 40 mph with gusts as high as 60 mph. All major highways were shut down by early afternoon, stranding thousands of holiday travelers and last-minute Christmas shoppers. The snow finally moved east during the early evening hours, leaving behind snow drifts as high as five feet, and streets littered with abandoned cars.

Statistic Value Year % of years Average Temperature 37.2 °F     Average Max Temp 47.2 °F     Average Min Temp 27.1 °F     # MaxTemps <= 32 14   11% # MaxTemps >= 70 3   2% # MinTemps <= 0 2   2% Warmest MaxT 73 °F 1922   Coldest MaxT 13 °F 1983   Warmest MinT 49 °F 1936   Coldest MinT -1 °F 1983           # Days with Precip 27   22% # Days with Snow 11   9% Rainfall > 0.10 5   4% Rainfall > 0.50 1   1% Rainfall > 1.00 1   1% Snowfall > 0.1 4   3% Snowfall > 0.5 2   2% Snowfall > 1.0 1   1% Snowfall > 2.0 1   1% Snowfall > 3.0 1   1% Snow depth >= T 11   9% Snow depth >= 1 6   5% Max Precip 1.05 in 1987   Max Snowfall 6.5 in 1914   Max Snow Depth 14 in 2009     Years with Snowfall on Christmas Day Snow on Ground on Christmas Morning 1913 Trace 1913 Trace 1914 6.5 inches 1914 6 inches 1937 Trace 1918 5 inches 1939 0.3 inches 1939 Trace 1948 Trace 1943 1 inch 1952 Trace 1962 Trace 1962 Trace 1975 1 inch 1975 0.5 inches 1983 Trace 1987 Trace 1987 Trace 2000  Trace 1990 Trace  2012 0.6 inches 2002 2 inches     2009 14 inches

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NWS Weather Facts for Christmas Day at Wichita Falls, Texas

The following are some numbers related to Christmas Day weather in Wichita Falls, TX. The numbers are based on records going back to 1923.

Some of the more memorable Christmas Days in recent years include... 1955: The high of 57 was above average by about 5 or 6 degrees, but it was a 30-degree drop-off from the previous day. A high of 87 on Christmas Eve was around 35 degrees above the long-term average, and is tied for the 2nd warmest daily temperature for December. 1983: Bitter cold with wind chills well below zero occurred during the pre-dawn hours of Christmas Day. The high of 14 was an improvement over the previous day, as the high on Christmas Eve was 11 degrees. 1989: Christmas Day was a sunny, mild day with temperatures well into the 60s. But what made this Christmas memorable was the dramatic warm-up that was in progress. Three days earlier the temperature fell to minus 4, breaking the previous all-time record low for December by two degrees. The next night, the December low temperature record was broken again when the temperature fell to minus 7. Two days later on Christmas Day, the temperature reached 65, giving Wichita Falls a  a 72-degree warm-up in just two days. 2009: Although no snow technically fell on Christmas Day, the record-setting blizzard that affected parts of north Texas on Christmas Eve was fresh on everyone's mind. Snow accumulated between 5 and 7 inches over a large area, with locations in Wichita and Clay counties reporting 7-10 inches! The snowstorm was made worse by the near continuous winds that were sustained near 40 mph with gusts as high as 60 mph. Most roadways were shut down by early afternoon, stranding thousands of holiday travelers and last-minute Christmas shoppers. The snow finally moved east during the early evening hours, leaving behind snow drifts as high as five feet, and streets littered with abandoned cars.

Statistic Value Year % of years Average Temperature 41.2 °F     Average Max Temp 53.0 °F     Average Min Temp 29.5 °F     # MaxTemps <= 32 2   2% # MaxTemps >= 70 7   7% # MinTemps <= 0 0   0% Warmest MaxT 75 °F 1942   Coldest MaxT 14 °F 1983   Warmest MinT 50 °F 1959   Coldest MinT 5 °F 1983           # Days with Precip 22   21% # Days with Snow 8   7% Rainfall > 0.10 6   6% Rainfall > 0.50 2   2% Rainfall > 1.00 1   1% Snowfall > 0.1 3   3% Snowfall > 0.5 2   2% Snowfall > 1.0 1   1% Snowfall > 2.0 1   1% Snowfall > 3.0 0   0% Snow depth >= T 4   9% Snow depth >= 1 2   5% Max Precip 1.97 in 1987   Max Snowfall 2.5 in 2012   Max Snow Depth 8 in 2009     Years with Snowfall on Christmas Day 1939 Trace 1975 0.3 inches 1983 Trace 1985 Trace 1987 1.0 inch 1997 Trace 2007 Trace 2012 2.5 inches

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