2011 Climate Information

 The year of 2011 started out wet across all of the region with much above normal snowfall  with  subsequent melting and widespread flooding. The wet conditions and flooding continued into summer.  The area started to dry out around August with the dry conditions remaining through the fall and through December.  Drought conditions developed and worsened across much of northeast South Dakota from the late summer and through the fall. The yearly precipitation data shows this as Watertown, Wheaton, and Sisseton all finished out the year with below normal precipitation.  Locations from the James Valley and west to the Missouri River finished out the year with above normal precipitation.  Pierre was nearly 6 inches above normal for the year. The biggest story of the year was the historic flooding on the Missouri River across South Dakota and especially in the Pierre area.  The other story was the late July heat wave experienced across the region. The high humidity and hot temperatures brought some record heat index readings to the region of 115 to 125 degrees.  The fall across northeast South Dakota and west central Minnesota was one of the top driest falls on record.  The winter has also begun dry across much of the region with brown conditions along with much above normal temperatures for December.

Monthly Summaries: 

Cold and Snowy January: The weather pattern remained unchanged throughout January with one Alberta Clipper after another followed by pushes of Arctic air. This pattern again brought much below normal temperatures and above normal snowfall for January across central and northeast South Dakota as well as west central Minnesota.   Average monthly temperatures across the region were from 3.5 to 5.4 degrees below normal while snowfall was anywhere from 5 to 14 inches above normal.  Snowfall amounts ranged from 12.9 inches at Pierre to 20.4 inches at Watertown. All of the monthly snowfall totals for January were in the top ten snowiest for all eight locations. Mobridge and Kennebec had their third snowiest Januarys on record with 18 and 19 inches, respectively. Watertown had its fourth snowiest January with 20.4 inches.   Pierre and Timber Lake had their fifth snowiest January with 12.9 and 17 inches, respectively.  Aberdeen had its 8^th snowiest January, while Sisseton and Wheaton both had their 9^th snowiest January on record.  The water equivalent of 1.54 inches at Watertown was their seventh wettest January on record.

Top Five Snowiest Februarys on Record: Much below normal temperatures and much above normal snowfall continued across central and northeast South Dakota as well as west central Minnesota for February 2011.  Despite the mid-February warm up and snowmelt across the region, average temperatures for February ranged from 5 to 9 degrees below normal.   The total snowfall for the month ranged from near 7 inches to almost 22 inches or  1 to 16 inches above normal.  The mid-February warm up from the 11-17^th brought high temperatures in the 30s and 40s across the region with some 50s and lower 60s in central and north central South Dakota. Pierre and Kennebec rose to the mid to upper 60s on February 16^th. This warm up was able to melt off quite a bit of the snow cover across the region.  Unfortunately, another strong upper level low pressure system brought widespread heavy snow along with blizzard conditions to the region on February 20^th.  Snowfall amounts from this system generally ranged from 10 to 20 inches replacing much of the previously melted snow cover.  This heavy snowfall brought most of the locations across the region into their top five snowiest Februarys on record.  The rankings included Sisseton with their second snowiest February on record; Wheaton with their third snowiest February;  Aberdeen and Pierre with their fourth snowiest; Watertown and Mobridge with their fifth snowiest February while Kennebec had their eight snowiest February on record. The February 20^th blizzard also broke several calendar day records for several locations across the region.   The 14 inches of snowfall at Watertown on February 20^th tied for 3^rd all time for calendar day snowfall and broke the record for snowiest calendar day for any day in February.  The 16 inches of snowfall at Aberdeen on February 20^th was the highest calendar day total for any day in February and was tied for 4^th all-time snowfall on any given calendar day. Finally, the 11.8 inches of snowfall at Pierre on February 20^th was the 2^nd snowiest calendar day in any February and 6^th snowiest calendar day all-time. February 2011 was also a very cold month with average temperatures ranging from 10 to 19 degrees putting most locations in their top 25 coldest Februarys of all-time.  Although February 2011 was below normal, it does not even come close to the all-time coldest February on record for the region.  February 1936 was brutally cold across the region with average monthly temperatures from minus 4 to minus 9 degrees or 17 to 23 degrees colder than February 2011. The average monthly temperature at Aberdeen in February 1936 was minus 8.1 degrees. February 1936’s average monthly temperatures were a whopping 24 to 31 degrees below normal across central and northeast South Dakota as well as west central Minnesota.  Specifically, February 1936 in Aberdeen was 26.8 degrees below normal and Timber Lake was 31 degrees below normal.

Much Below Normal March Temperatures: March 2011 kept the string of cold months going across central and north central South Dakota, as well as west central Minnesota, with much below normal temperatures.  For most locations across the region, March 2011 was one of the top fifteen coldest on record. Average temperatures for the month were from 6 to 10 degrees below normal.  The 21.4 degrees at Sisseton was the third coldest on record. The 20.1 degree monthly average at Wheaton was the fifth coldest on record.  Aberdeen’s monthly average temperature for March was 21.1 degrees which is the seventh coldest on record.  The monthly average temperature for Mobridge was 22.2 degrees, which is the 9^th coldest March on record. It was very cold to start the month with low temperatures in the single digits to teens below zero.  A warm up in the middle of the month brought highs into the mid 40s to mid 50s across north central and northeast South Dakota, as well as west central Minnesota.  With the lack of snow cover in central South Dakota, temperatures warmed into the mid 60s to around 70 degrees. This warm up brought a lot of snow melt and runoff with subsequent flooding, especially across northeast South Dakota and west central Minnesota.  Most rivers, creeks, and lakes rose above flood stage across northeast South Dakota.  With a cool down and decreasing runoff towards the end of the month, most of the creeks and rivers fell back below flood stage. Although, with more snow yet to melt across northeast South Dakota and west central Minnesota, creek and river rises are expected again across the region. March precipitation and snowfall was not too far off from normal for the month for most locations. The exception was for snowfall at Mobridge and Timber Lake where they received around 13 to 14 inches of snow for the month.  These amounts were about 5 to 6 inches above normal. Also, thunderstorms brought heavy rain to parts of northeast South Dakota on March 22^nd where .75 to near 1.25 inches of rainfall occurred.  This only worsened much of the flooding, especially in Hamlin County. 

April Climate Information: Much below normal temperatures continued across central and northeast South Dakota as well as west central Minnesota in April. Average highs for April across the region were from 4 to 7 degrees below normal while the average lows were near to a few degrees below normal.  The overall average temperatures for the month were from 2 to 4 degrees below normal. Monthly precipitation was below normal for some locations and much above for other locations. Flooding continued to be a big issue across much of the region throughout April, especially across northeast South Dakota.  The big weather event for the month was in the mid April when a large snowstorm brought 6 to 15 inches of snowfall to the region.

Cool and Wet May: May 2011 continued the string of months with below normal temperatures and above normal precipitation.  The average temperatures for May were from 2 to nearly 5.5 degrees below normal across the region.  The train of strong upper level low pressure systems kept rolling over the region bringing 3 to over 4 inches of rainfall for May.  The average highs were well below normal ranging from 4 to 8 degrees below normal.  With the cooler temperatures, severe weather was also kept at a minimum for the month. Flooding also continued throughout the month mainly along the James River and on Lake Poinsett.

Cooler and Wetter Than Normal June: The trend of cooler and wetter than normal conditions continued across the area for June as the relentless parade of upper level low pressure systems moved across the region from the Pacific Northwest.  June 2011 across central and northeast South Dakota along with west central Minnesota was generally wetter and cooler than normal.  June average temperatures were from a half degree to nearly 4 degrees below normal. There were only a couple big warm-ups during the month with the highest temperatures reaching the 90s with no location reaching the 100 degree mark. The rainfall for June was generally above to much above normal, especially across central and north central South Dakota. Watertown was the only location with slightly below normal rainfall.  June rainfall ranged from 4 to 8 inches across the region. Pierre received the most rainfall for the month with 8.31 inches, almost 5 inches above normal. The 8.31 inches of rainfall at Pierre broke the all-time June rainfall record along with the all-time precipitation record for any month. The big rainfall event for the month was from June 19^th through June 21st when a winter or early spring type strong upper level low pressure system brought widespread heavy rainfall to the region.  The heavy rainfall created more flooding along with worsening the ongoing flooding, especially along the Missouri River.  Rainfall amounts from this storm ranged anywhere from 1 to almost 7 inches across the area.  The seven inches of rainfall created flash flooding along with a two deaths near Fort Thompson in central South Dakota.

Warm and Humid July: July 2011 was a very warm and generally wet month across most of central and northeast South Dakota along with west central Minnesota.  Monthly average temperatures were anywhere from 1 to 5 degrees above normal.  The most notable temperatures were the average lows across the region which ranged from 2 to 7 degrees above normal.  Much of July was humid with dew points regularly in the 60s and 70s. In fact, several times dew points reached 80 degrees or higher at several locations.  Aberdeen tied for its highest dew point with 82 degrees.  Overnight lows were quite warm due in part to the high moisture in the air which allowed less heat to escape at night.  The high temperatures for the month were mostly in the upper 90s to the lower 100s with Kennebec reaching 105 degrees on the 19^th. The high humidity along with the hot temperatures brought a period of excessive heat to the area from July 15^th through July 20^th.  Heat Index readings were regularly in the 105 to 115 degree range through this time period.  During this time, Milbank reached a heat index of 120 degrees, Aberdeen reached a heat index of 121 degrees, while Leola reached 125 degrees. The precipitation for July was above to much above normal in northeast South Dakota and west central Minnesota while it was below normal across parts of central and north central South Dakota.  In fact, a couple heavy rain events brought a very wet month to Aberdeen and Wheaton. Aberdeen had its fourth wettest July on record receiving 6.63 inches of rainfall which was 3.71 inches above normal.  Wheaton set the July record for the wettest month receiving a whopping 8.01 inches of rain. This amount was 4.90 inches above normal. With another wet month across northeast South Dakota and west central Minnesota, flooding continued to be a big issue across the area.

August 2011 Climate Information: August 2011 temperatures across central and northeast South Dakota as well as west central Minnesota were generally near to slightly above normal. Average temperatures were from just a few tenths below to a couple degrees above normal for August. Wheaton was the coolest location at 1.5 degrees below average. The warmest temperatures for the month were in central and north central South Dakota with highs in the lower 100s. The precipitation for August was above and below for several areas across the region. Aberdeen and Watertown dried out some through August with both locations around an inch and a half below normal.  As a result, the drought monitor was now showing an abnormally dry area extending across much of northeast South Dakota.  Sisseton was over an inch above normal for August as the northern part of Roberts County, especially in the New Effington area, received quite a bit of rainfall in August.  This heavy rain caused flash flooding in the New Effington area two separate times. The Missouri River continued to fall throughout the month across central and north central South Dakota as dam releases were lowered.  

Dry September: September dried out across central and northeast South Dakota as well as west central Minnesota with all locations having much below normal precipitation for the month.  September rainfall was from around an inch and a half to just over two inches below normal across northeast South Dakota and west central Minnesota.  The rainfall across central and north central South Dakota was around an inch below normal for the month. Wheaton and Watertown had one of their top ten driest Septembers on record.  Wheaton had their 7^th driest September on record while Watertown had their 8^th driest September.  Due to this dryness, the drought area expanded across the eastern part of the region from around Aberdeen to Watertown and south. The average temperatures for September across central and north central South Dakota as well as west central Minnesota were generally from 1 to 3 degrees cooler than normal.  Some very warm temperatures were also experienced at many locations at the end of the month.  Pierre, Watertown, and Sisseton all tied or broke their high temperature records on September 28^th with highs in the upper 80s and lower 90s.  On the cold side, most locations across the region experienced a frost in September with lows in the upper 20s and lower 30s.  A hard freeze of several hours of 28 degrees or lower has yet to be experienced.

Very Warm and Dry October: October 2011 across central and northeast South Dakota as well as west central Minnesota had much above normal temperatures with generally below normal precipitation.  Average monthly temperatures were from 4 to 6 degrees above normal across the region.   It was very warm early in the month with highs in the mid 80s to the mid 90s from the 4^th through the 6th.  The high for the month of 95 degrees at Pierre on the 4^th and the low of 19 degrees on the 20^th were both records for those days.  The lowest temperature for October was at Kennebec with 16 degrees. Precipitation for the month was generally just below to much below normal across the region.   The exception was Mobridge where the precipitation for the month was above normal with almost two and half inches of rainfall.  The eastern part of the region was the driest for the month with rainfall deficits of around an inch to an inch and a half for October.   

Very Dry and Warm November: November 2011 across central and northeast South Dakota along with west central Minnesota was much drier than normal along with warmer than normal temperatures.  The monthly average temperatures were anywhere from 1 to 4 degrees above normal across the region.  In November, snow cover and the James Valley’s affect on temperatures showed up at Kennebec, Pierre, and Aberdeen.  Both Pierre and Kennebec received snowfall on the 19^th with Pierre receiving nearly 10 inches.  This snow cover helped bring some cold temperatures to both locations.  The low temperature departures from normal at Pierre were from minus 10 to around 15 degrees from the 19^th through the 22^nd.   The daytime highs were also affected by the snow cover at Pierre with highs ranging from 24 to 33 degrees from the 19^th through the 22^nd.  Despite having no snow cover for November, Aberdeen still had slightly below normal low temperatures for the month.  The drainage effect of the colder air at night in the James Valley contributed to Aberdeen receiving some decent low temperatures for the month.   The lack of cloud cover for November also played a big role across the region for both high and low temperatures.   Normally, the area would be experiencing quite a bit of low stratus clouds throughout the month. The lack of cloud cover affected both high and low temperatures across the region.  During the day, the abundant sunshine combined with the lack of snow cover in some locations, allowed the temperatures to warm up nicely, while the lack of clouds allowed the temperatures to cool off quickly at night. 

Warm and Dry December: With mild Pacific west to northwest flow through the month, December 2011 was very warm and dry across central and northeast South Dakota as well as west central Minnesota.  With abundant sunshine along with the lack of snow cover, average temperatures for the month were from 6 to 10 degrees above normal.  Most locations had one of their top fifteen warmest Decembers with some in their top ten warmest.  Mobridge had their seventh warmest December on record.  The highest temperatures for the month were much above normal with highs in the 50s to around 60 degrees.  December usually experiences many nights with much below zero temperatures.  For this December, the lowest temperatures were only from zero to 10 degrees below zero across the region. The area was also dry for December with locations ranging from a tenth to a half of an inch of precipitation below normal for the month. As a result, the snowfall was scarce with monthly amounts ranging from only a trace to 1.5 inches.  These monthly amounts were from 4 to 7 inches below normal.  Several locations December snowfall amounts were in their top fifteen lowest with Watertown tying for the lowest all-time with only a trace of snowfall.  Also, most of the precipitation for December was rain which is a very rare occurrence for this time of year. It appears that we have taken a 180 degree turn from last December.   Looking back to December 2010, average temperatures were some 10 to 20 degrees colder across the region.  A majority of the difference in temperatures is owed to the thick snow cover in December 2010.  In fact, the snowfall amounts for December 2010 ranged from 8 inches at Timber Lake to 33 inches at Sisseton.