Douglas County climate

Douglas County Frost Dates and Growing Season

NOAA 1991-2020 normals for Lawrence, 8.9 km from Douglas County, elevation 1050 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lawrence. 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 12 and the first fall freeze around October 28, a growing season of about 199 days.

Median at 36°F
last April 21, first October 19
Median at 32°F
last April 12, first October 28
Median at 28°F
last April 3, first November 4

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 2Apr 29Apr 26Apr 23Apr 21Apr 18Apr 15Apr 13Apr 8
32°FApr 24Apr 20Apr 17Apr 14Apr 12Apr 9Apr 6Apr 3Mar 30
28°FApr 17Apr 11Apr 8Apr 5Apr 3Mar 31Mar 28Mar 23Mar 16
24°FApr 8Apr 3Mar 31Mar 29Mar 24Mar 21Mar 17Mar 13Mar 6
20°FMar 31Mar 26Mar 21Mar 17Mar 13Mar 10Mar 6Mar 2Feb 25
16°FMar 21Mar 15Mar 11Mar 7Mar 4Mar 1Feb 26Feb 21Feb 13

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°FOct 2Oct 8Oct 12Oct 15Oct 19Oct 21Oct 23Oct 26Oct 31
32°FOct 14Oct 19Oct 22Oct 25Oct 28Oct 31Nov 2Nov 5Nov 9
28°FOct 22Oct 28Oct 31Nov 2Nov 4Nov 7Nov 10Nov 14Nov 20
24°FOct 31Nov 3Nov 6Nov 10Nov 13Nov 16Nov 20Nov 25Dec 1
20°FNov 5Nov 11Nov 14Nov 19Nov 23Nov 27Dec 1Dec 4Dec 10
16°FNov 12Nov 20Nov 26Nov 30Dec 3Dec 6Dec 11Dec 16Dec 22

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°F197191187183179175171167159
32°F217211206202199195190185178
28°F240230224220216212208203197
24°F259250244238234229225220212
20°F276269264258253248243237230
16°F295287281276271266261254245

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
5,089
Cooling degree days, base 65°F
1,446
Growing degree days, base 40°F
6,550
Growing degree days, base 45°F
5,263
Growing degree days, base 50°F
4,113
Growing degree days, base 55°F
3,093
Growing degree days, base 60°F
2,205

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,12002
February888010
March659364
April33916193
May107107468
June6294738
July0440905
August2387851
September51167567
October28430256
November641253
December99207

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 8.9 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 USC00144559 (Lawrence). Public domain.