Cleburne County climate

Cleburne County Frost Dates and Growing Season

NOAA 1991-2020 normals for Heflin, 9 km from Cleburne County, elevation 1000 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Heflin. 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 6 and the first fall freeze around October 31, a growing season of about 206 days.

Median at 36°F
last April 20, first October 22
Median at 32°F
last April 6, first October 31
Median at 28°F
last March 25, first November 9

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 4Apr 30Apr 26Apr 23Apr 20Apr 17Apr 13Apr 9Apr 4
32°FApr 22Apr 17Apr 13Apr 9Apr 6Apr 3Mar 31Mar 27Mar 20
28°FApr 10Apr 6Apr 2Mar 30Mar 25Mar 22Mar 18Mar 13Mar 2
24°FMar 31Mar 25Mar 20Mar 15Mar 11Mar 6Feb 28Feb 23Feb 14
20°FMar 19Mar 11Mar 4Feb 28Feb 23Feb 17Feb 10Feb 3Jan 26
16°FMar 5Feb 26Feb 18Feb 10Feb 4Jan 31Jan 26Jan 19Jan 8

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 14Oct 17Oct 19Oct 22Oct 24Oct 27Oct 30Nov 2
32°FOct 19Oct 23Oct 25Oct 29Oct 31Nov 2Nov 5Nov 8Nov 12
28°FOct 27Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 20Nov 28
24°FNov 5Nov 9Nov 14Nov 17Nov 22Nov 26Dec 1Dec 6Dec 14
20°FNov 16Nov 24Nov 30Dec 4Dec 8Dec 15Dec 24Jan 1Jan 7
16°FDec 1Dec 6Dec 16Dec 25Jan 1Jan 4Jan 9Jan 17Jan 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°F204198193188184180177172165
32°F226219215211206202198193186
28°F255247240235230224219214206
24°F290278269263257251245238229
20°F328315305298291284275266254
16°F362345336331324316306297284

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
93% 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
3,193
Cooling degree days, base 65°F
1,474
Growing degree days, base 40°F
7,635
Growing degree days, base 45°F
6,076
Growing degree days, base 50°F
4,671
Growing degree days, base 55°F
3,430
Growing degree days, base 60°F
2,366

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January729032
February558149
March4025151
April19029305
May51126540
June3279726
July0394859
August0372837
September16217651
October16446358
November4365116
December646148

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 9 km from Cleburne 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 USC00013775 (Heflin). Public domain.