Spring 2018 Frost/Freeze Information...We're "95% Sure" There Will Be No Further Risk This Spring!

** PLEASE NOTE: NWS Hastings WILL ISSUE official Freeze Warnings/Frost Advisories (as needed) the rest of the Spring **

General Overview of Local Spring Frost/Freeze Information:
The mid-April through early-May time frame typically features the last occurrence of freezing temperatures and/or frost in South Central Nebraska and North Central Kansas for the spring season...(Click HERE for a map of the 30-county NWS Hastings Area). Based on 30-year averages, the date of the average last spring freeze (32°-or-colder) ranges from around April 18th in far southeast local communities such as Beloit KS, to around April 23-30 in the Tri Cities (Grand Island/Hastings/Kearney), and around May 5th in far northern and western communities such as Greeley, Gothenburg and Cambridge. HOWEVER, after seeing the maps and tables contained in this story, it should be readily apparent that the phrase "average last freeze date" is quite relative, as most sites exhibit a 6-9 week difference between the earliest and last dates!

Please refer to the wealth of information within the tabs below (including tables and maps of average last frost/freeze/hard freeze dates) to "stay on top" of the frost/freeze situation across the local area this spring.

Looking Ahead: Has The Last Spring 2018 Frost/Freeze Already Occurred?
(updated May 17)

THE SHORTER TERM (next 7 days through May 24): At this time, there are NO risks for frost/freezing temperatures anywhere in our local area.

THE LONGER TERM (beyond the next week): Now that we are into the latter half of May and there are still no hints of sub-freezing temperatures in sight through AT LEAST the next 7 days, our confidence is increasing that we are most likely "in the clear". Based on the wealth of historical averages/extremes data found in this story, sub-freezing conditions are VERY RARE within our coverage area during the latter one-third of May, and have NEVER OCCURRED IN JUNE. At this point, we are declaring with roughly "95% confidence" that frost/freeze issues will not be a concern going forward this spring, and this particular story will be "dropped" from the top of our web page in a few days.

Recapping Last Spring's (2017) Final Frost/Freeze:

- Spring 2017: For the vast majority of the NWS Hastings coverage area, the last freeze of spring 2017 occurred near-to-slightly later than the 30-year average (see table below). More specifically, most places observed their last freeze and/or hard freeze during the April 27-May 1 time frame. More remarkably, many places (especially within the northern and western fringes of the local area) also received very late-season SNOW during this period as well (click here for a separate story about this snow storm)! As for frost potential, some places reported readings as low as 33-36º as late as May 21-24. Overall though, there were no major horticultural/agricultural impacts associated with any slightly-later-than-average frost/freeze conditions during spring 2017.

Frost/Freeze Definitions
Maps & Table of Average Frost/Freeze Dates
Daily Frost/Freeze Maps
Spring First Leaf/Bloom Index Maps

Before continuing, here are a few definitions...

Frost

Frost occurs when there is a solid deposition of water vapor from the air. Frost will form when solid surfaces are cooled below the dew point. An air temperature range of 33°- 36° (or colder), along with light winds, is usually needed to initiate frost formation. At least minor damage is possible to plants. One must keep in mind that despite cold temperatures, a frost is not "guaranteed" if moisture in the air is lacking and/or winds are strong.

The range of average dates for the LAST frost of the spring across across most of
south central Nebraska and north central Kansas is between May 1-May 16.

Freeze

Freeze occurs when the air temperature drops to 32°-or-lower. A freeze will result in significant damage to many unprotected plants, especially if the temperature remains at-or-below the freezing mark for several hours.

The range of average dates for the LAST spring freeze across most of
south central Nebraska and north central Kansas is between April 18-May 6.

Hard Freeze

Hard freeze (per our local NWS definition) occurs when the temperature reaches 28°-or-lower for at least a few hours. It usually means that many types of plants and most seasonal vegetation will be destroyed.

The range of average dates for the LAST hard freeze of the spring across across most of
south central Nebraska and north central Kansas is between April 7-April 28.

South Central Nebraska and North Central Kansas
30-Year Average Last Frost/Freeze Dates (1988-2017)
(click image to enlarge)


Average Last 36° Date (Last Spring Frost)	Average Last 32° Date (Last Spring Freeze)	Average Last 28° Date (Last Spring Hard Freeze)

Median Dates of Last Spring Freeze & Hard Freeze (1981-2010)
(Midwestern Regional Climate Center)


Median Date of Last Spring 32° Freeze	Median Date of Last Spring 28° Hard Freeze

Below is a table focused on the average dates for reaching particular frost/freeze temperature thresholds. Keep in mind, there is often tremendous variation from year-to-year and between any given location across the area!

Here is how to interpret the following table:

The first column lists 10 locations in south central Nebraska and 3 in north central Kansas with long histories of being NWS Cooperative Observer sites (except for Grand Island and Hastings airports, which have been automated systems since the 1990s). This is just a small sampling of dozens of official weather stations within the NWS Hastings coverage area, and these sites are generally organized down the column from north-to south.
The second column shows the average date of the LATEST observance of 28°, 32° and 36° temperatures during the most recent 30-year period from 1988-2017.
The third and fourth columns reveal the earliest last freeze date and latest last freeze date (32° or colder) during the past 30 years. It is readily apparent that the phrase "average last freeze date" is quite relative, as most sites have a 6-9 week difference between the earliest and latest dates. For some of these locations, the incredibly-early last freeze of spring 2012 (between March 9-11) was among the earliest on record. On the opposite spectrum, for several places, the latest freeze of the past 30 years occurred just four years ago in mid-May 2014.
The final column is a recap of LAST SPRING (2017), showing the actual last dates that 28°, 32° and 36° were observed. A blue-shaded date indicates that the last spring frost/freeze/hard freeze of 2017 was more than 10 days LATER than the 30-year average, while red-shaded dates indicate a last spring frost/freeze/hard freeze that was more than 10 days EARLIER-than-normal. If a date is neither blue nor red, then it fell within 10 days of the 30-year average (near-normal).

Spring Frost/Freeze Data For South Central Nebraska and North Central Kansas
(all averages based on 30-year observations from 1988-2017)

	Avg Last Spring Date Of: 28° Or Colder 32° Or Colder 36° Or Colder	1988-2017 Earliest Last Date Of: 32° Or Colder	1988-2017 Latest Last Date Of: 32° Or Colder	Last Spring 2017 Date Of: 28° Or Colder 32° Or Colder 36° Or Colder
Greeley	April 28 May 6 May 16	April 16, 2007	May 19, 2000	April 28 (24º) May 1 (32º) May 22 (35º)
Osceola	April 14 April 26 May 4	March 31, 1991	May 15, 2014	April 28 (27º) May 2 (32º) May 2 (32º)
Gothenburg	April 21 May 4 May 15	April 11, 2012	May 28, 1992	April 27 (28º) May 1 (32º) May 24 (36º)
Kearney Airport (NWS Observer)	April 21 April 30 May 11	April 10, 2003	May 28, 1992	April 27 (28º) April 30 (32º) May 22 (35º)
Grand Island (airport)	April 14 April 26 May 6	April 9, 2003	May 17, 2014	April 27 (25º) May 1 (32º) May 1 (32º)
Holdrege	April 14 May 2 May 8	April 10, 2003	May 29, 1992	April 29 (26º) May 1 (32º) May 22 (33º)
Hastings (airport)	April 11 April 23 May 4	March 9, 2012	May 17, 2014	April 27 (27º) April 27 (27º) May 1 (33º)
Geneva	April 7 April 20 May 1	March 9, 2012	May 17, 2014	April 11 (25º) May 1 (32º) May 1 (32º)
Cambridge	April 20 May 4 May 13	April 8, 2003	May 29, 1992	April 27 (28º) May 5 (32º) May 21 (36º)
Hebron	April 11 April 24 May 4	March 11, 2012	May 16, 2014	April 27 (28º) April 28 (29º) May 2 (34º)
Smith Center, KS	April 8 April 20 May 2	March 10, 2012	May 6, 1989	April 28 (28º) May 1 (32º) May 22 (36º)
Plainville, KS (4 miles WNW)	April 9 April 22 May 5	March 10, 2012	May 12, 2008	March 16 (23º) May 2 (32º) May 2 (32º)
Beloit, KS	April 7 April 18 May 1	March 11, 2012	May 6, 1989	April 27 (28º) April 27 (28º) May 1 (33º)

The Midwestern Regional Climate Center (MRCC) produces maps that update DAILY, depicting the most recent date that sites across the region that have fallen to at least 32° or 28° this spring. In addition, GRAY shaded areas = places that have NOT YET accumulated at least 150 traditionally-calculated Growing Degree Days (GDD) since Feb. 1. In general, this means that gray-shaded areas have not yet become favorable for widespread plant/crop growth.

Check out the statewide maps of Kansas and Nebraska by clicking on the images below. These maps originate from the Midwestern Regional Climate Center website.


*KS: Most Recent 32° or Below* This Spring**	*NE: Most Recent 32° or Below* This Spring**

*KS: Most Recent 28° or Below* This Spring**	*NE: Most Recent 28° or Below* This Spring**

The USA-National Phenology Network (NPN) produces several maps that update DAILY, depicting the progression of particular types of spring vegetation across the nation, and how it compares to long-term averages. See their web page for much more detail and information, but the two maps highlighted below depict First Leaf Index Anomaly and First Bloom Index Anomaly. In short, this means they show the current status of some types of spring vegetation (first leaf-out or first-flowering) compared to long-term averages, giving an idea of whether spring is "ahead" of or "behind" schedule.


Spring Leaf Index Anomaly	Spring Bloom Index Anomaly

Media use of NWS Web News Stories is encouraged!
Please acknowledge the NWS as the source of any news information accessed from this site.