Douglas County climate

Douglas County Frost Dates and Growing Season

NOAA 1991-2020 normals for Wasola 5N, 11.5 km from Douglas County, elevation 1226 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wasola 5N. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around April 10 and the first fall freeze around October 27, a growing season of about 198 days.

Median at 36°F
last April 23, first October 16
Median at 32°F
last April 10, first October 27
Median at 28°F
last March 31, first November 5

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 8May 3Apr 30Apr 26Apr 23Apr 19Apr 15Apr 12Apr 6
32°FApr 26Apr 20Apr 16Apr 12Apr 10Apr 7Apr 4Mar 31Mar 26
28°FApr 14Apr 9Apr 5Apr 3Mar 31Mar 28Mar 24Mar 19Mar 12
24°FApr 4Mar 31Mar 27Mar 23Mar 19Mar 16Mar 12Mar 6Feb 28
20°FMar 27Mar 21Mar 17Mar 12Mar 8Mar 5Mar 1Feb 25Feb 18
16°FMar 18Mar 12Mar 7Mar 3Feb 28Feb 23Feb 18Feb 13Feb 5

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 30Oct 6Oct 10Oct 14Oct 16Oct 19Oct 22Oct 24Oct 29
32°FOct 14Oct 18Oct 21Oct 24Oct 27Oct 29Nov 1Nov 4Nov 9
28°FOct 22Oct 27Oct 31Nov 2Nov 5Nov 7Nov 12Nov 17Nov 24
24°FNov 1Nov 5Nov 8Nov 12Nov 16Nov 21Nov 25Dec 1Dec 5
20°FNov 8Nov 15Nov 21Nov 25Nov 28Dec 1Dec 5Dec 10Dec 16
16°FNov 19Nov 26Dec 1Dec 5Dec 8Dec 13Dec 17Dec 22Dec 29

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F197189184180175171166161154
32°F220213208203198195189184177
28°F245238233227223218214208200
24°F269259253248244238233226218
20°F291282276269264258252246238
16°F312303296290285279273266256

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
4,526
Cooling degree days, base 65°F
1,203
Growing degree days, base 40°F
6,544
Growing degree days, base 45°F
5,185
Growing degree days, base 50°F
3,970
Growing degree days, base 55°F
2,900
Growing degree days, base 60°F
1,977

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January98908
February774018
March586485
April28518227
May10582445
June8235676
July1362826
August2335798
September50141542
October26324260
November577269
December887014

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 11.5 km from Douglas County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00238754 (Wasola 5N). Public domain.