Grady County climate

Grady County Frost Dates and Growing Season

NOAA 1991-2020 normals for Chickasha Exp Station, 4.6 km from Grady County, elevation 1085 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Chickasha Exp Station. 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 4 and the first fall freeze around November 1, a growing season of about 211 days.

Median at 36°F
last April 14, first October 23
Median at 32°F
last April 4, first November 1
Median at 28°F
last March 24, first November 8

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°FApr 28Apr 23Apr 20Apr 17Apr 14Apr 11Apr 8Apr 5Mar 31
32°FApr 20Apr 14Apr 10Apr 7Apr 4Apr 2Mar 29Mar 25Mar 20
28°FApr 8Apr 4Mar 31Mar 27Mar 24Mar 20Mar 15Mar 11Mar 4
24°FMar 30Mar 23Mar 18Mar 15Mar 11Mar 7Mar 4Feb 28Feb 23
20°FMar 18Mar 12Mar 7Mar 3Feb 28Feb 25Feb 20Feb 14Feb 4
16°FMar 8Mar 3Feb 26Feb 22Feb 15Feb 8Feb 2Jan 28Jan 17

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 9Oct 15Oct 18Oct 21Oct 23Oct 27Oct 29Nov 1Nov 6
32°FOct 18Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 10Nov 15
28°FOct 25Oct 31Nov 2Nov 5Nov 8Nov 12Nov 16Nov 21Nov 26
24°FNov 1Nov 6Nov 11Nov 15Nov 19Nov 23Nov 26Dec 1Dec 6
20°FNov 10Nov 17Nov 23Nov 26Nov 29Dec 3Dec 6Dec 12Dec 21
16°FNov 21Nov 28Dec 3Dec 8Dec 14Dec 20Dec 25Jan 1Jan 10

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°F210205200196192188184179172
32°F233224220215211207203196190
28°F255246241236232227221216208
24°F278270264259254248243237228
20°F304295286280274268264257248
16°F336326318309303296289281270

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
99% 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
3,192
Cooling degree days, base 65°F
2,250
Growing degree days, base 40°F
8,483
Growing degree days, base 45°F
6,943
Growing degree days, base 50°F
5,552
Growing degree days, base 55°F
4,304
Growing degree days, base 60°F
3,205

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January770022
February587147
March38812174
April15064375
May23214656
June1427876
July05841,049
August05451,010
September12310748
October13083427
November4189137
December713031

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 4.6 km from Grady County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00341750 (Chickasha Exp Station). Public domain.