Limestone County climate

Limestone County Frost Dates and Growing Season

NOAA 1991-2020 normals for Athens, 4.7 km from Limestone County, elevation 689 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Athens. 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 March 20 and the first fall freeze around November 12, a growing season of about 238 days.

Median at 36°F
last April 4, first November 1
Median at 32°F
last March 20, first November 12
Median at 28°F
last March 6, first November 24

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 19Apr 14Apr 10Apr 6Apr 4Apr 1Mar 29Mar 24Mar 17
32°FApr 7Apr 2Mar 29Mar 24Mar 20Mar 17Mar 13Mar 8Mar 1
28°FMar 26Mar 20Mar 16Mar 11Mar 6Mar 1Feb 26Feb 21Feb 13
24°FMar 15Mar 6Mar 1Feb 25Feb 19Feb 14Feb 9Feb 2Jan 26
20°FMar 3Feb 24Feb 16Feb 10Feb 4Jan 31Jan 25Jan 17Jan 8
16°FFeb 20Feb 9Feb 3Jan 31Jan 26Jan 20Jan 14Jan 8Dec 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 22Oct 25Oct 28Oct 31Nov 1Nov 4Nov 7Nov 10Nov 15
32°FNov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 18Nov 24Dec 1
28°FNov 6Nov 12Nov 16Nov 20Nov 24Nov 29Dec 2Dec 7Dec 18
24°FNov 16Nov 25Dec 1Dec 4Dec 10Dec 19Dec 25Jan 1Jan 9
20°FDec 2Dec 10Dec 21Dec 27Jan 1Jan 5Jan 10Jan 16Jan 29
16°FDec 20Dec 29Jan 1Jan 5Jan 9Jan 14Jan 18Jan 27Feb 5

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°F237228223218214209205200193
32°F265255248243238232228223215
28°F295284277269264259252245236
24°F327317308301294287280272263
20°F362346336330324317310302291
16°F365365365355347340334327314

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
93% of years
16°F or colder
68% 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
2,889
Cooling degree days, base 65°F
2,028
Growing degree days, base 40°F
8,473
Growing degree days, base 45°F
6,885
Growing degree days, base 50°F
5,436
Growing degree days, base 55°F
4,137
Growing degree days, base 60°F
2,999

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January701146
February525264
March35716193
April14463379
May31198633
June1384832
July0496961
August0476941
September9300741
October12482430
November38610152
December612364

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 4.7 km from Limestone 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 USC00010390 (Athens). Public domain.