Donley County climate

Donley County Frost Dates and Growing Season

NOAA 1991-2020 normals for Clarendon, 7.8 km from Donley County, elevation 2700 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Clarendon. 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 14 and the first fall freeze around October 26, a growing season of about 194 days.

Median at 36°F
last April 24, first October 17
Median at 32°F
last April 14, first October 26
Median at 28°F
last April 3, first November 3

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 6May 2Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 10
32°FApr 28Apr 24Apr 20Apr 17Apr 14Apr 11Apr 7Apr 3Mar 29
28°FApr 21Apr 14Apr 10Apr 6Apr 3Apr 1Mar 27Mar 23Mar 15
24°FApr 8Apr 2Mar 30Mar 25Mar 20Mar 16Mar 12Mar 7Mar 2
20°FMar 30Mar 21Mar 15Mar 11Mar 7Mar 4Feb 28Feb 25Feb 19
16°FMar 14Mar 8Mar 3Feb 28Feb 24Feb 19Feb 15Feb 9Jan 31

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 5Oct 9Oct 13Oct 15Oct 17Oct 19Oct 22Oct 25Oct 29
32°FOct 15Oct 18Oct 21Oct 24Oct 26Oct 29Nov 1Nov 3Nov 7
28°FOct 22Oct 26Oct 30Nov 1Nov 3Nov 6Nov 8Nov 12Nov 17
24°FOct 30Nov 3Nov 6Nov 9Nov 12Nov 15Nov 18Nov 23Nov 29
20°FNov 8Nov 12Nov 15Nov 19Nov 22Nov 25Nov 30Dec 4Dec 9
16°FNov 15Nov 21Nov 25Nov 28Dec 2Dec 6Dec 10Dec 15Dec 25

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°F194187182178175171168164158
32°F214208202198194190186181175
28°F239230223218214209204198191
24°F261253247242237231225219212
20°F284275270264259254249243232
16°F313303296288283277271265258

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
3,833
Cooling degree days, base 65°F
1,748
Growing degree days, base 40°F
7,504
Growing degree days, base 45°F
6,044
Growing degree days, base 50°F
4,732
Growing degree days, base 55°F
3,582
Growing degree days, base 60°F
2,591

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January832014
February660131
March4806119
April24131273
May70146543
June3357804
July0490955
August1448913
September28225647
October20542325
November518390
December795018

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 7.8 km from Donley 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 USW00023072 (Clarendon). Public domain.