Austell climate

Austell Frost Dates and Growing Season

NOAA 1991-2020 normals for Mableton 1 N, 6.8 km from Austell, elevation 980 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mableton 1 N. 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 27 and the first fall freeze around November 7, a growing season of about 225 days.

Median at 36°F
last April 8, first October 30
Median at 32°F
last March 27, first November 7
Median at 28°F
last March 14, first November 19

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 24Apr 19Apr 15Apr 11Apr 8Apr 5Apr 2Mar 30Mar 23
32°FApr 12Apr 7Apr 3Mar 31Mar 27Mar 23Mar 19Mar 16Mar 9
28°FMar 31Mar 26Mar 21Mar 17Mar 14Mar 10Mar 5Feb 28Feb 21
24°FMar 21Mar 16Mar 10Mar 6Mar 1Feb 24Feb 19Feb 9Jan 31
20°FMar 13Mar 3Feb 25Feb 17Feb 9Feb 1Jan 28Jan 21Jan 9
16°FMar 1Feb 16Feb 5Jan 31Jan 27Jan 22Jan 16Jan 10Jan 2

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 19Oct 23Oct 25Oct 28Oct 30Nov 1Nov 3Nov 6Nov 10
32°FOct 27Oct 31Nov 3Nov 5Nov 7Nov 10Nov 14Nov 19Nov 26
28°FNov 4Nov 8Nov 12Nov 16Nov 19Nov 23Nov 29Dec 3Dec 9
24°FNov 14Nov 20Nov 26Dec 1Dec 4Dec 8Dec 17Dec 27Jan 4
20°FNov 26Dec 4Dec 11Dec 20Dec 27Jan 1Jan 6Jan 13Jan 24
16°FDec 10Dec 22Dec 30Jan 2Jan 6Jan 13Jan 17Jan 24Feb 3

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°F225218212208204200196191184
32°F249241236230225221217213205
28°F281270262255250245240234225
24°F318304296287279273265258249
20°F348336329321314306298288277
16°F365365357348339333326312300

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
96% of years
16°F or colder
75% 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
3,051
Cooling degree days, base 65°F
1,309
Growing degree days, base 40°F
7,542
Growing degree days, base 45°F
5,945
Growing degree days, base 50°F
4,519
Growing degree days, base 55°F
3,272
Growing degree days, base 60°F
2,203

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January698031
February533147
March3868157
April18030314
May49109526
June2264712
July0344809
August0333798
September14184619
October16133346
November4134110
December616050

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 6.8 km from Austell. 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 USC00095404 (Mableton 1 N). Public domain.