Athens climate

Athens Frost Dates and Growing Season

NOAA 1991-2020 normals for Harmony, 10.4 km from Athens, elevation 320 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Harmony. 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 May 11 and the first fall freeze around October 1, a growing season of about 141 days.

Median at 36°F
last May 24, first September 20
Median at 32°F
last May 11, first October 1
Median at 28°F
last April 30, first October 11

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°FJun 5Jun 1May 29May 26May 24May 21May 18May 14May 9
32°FMay 25May 21May 17May 13May 11May 8May 5May 3Apr 30
28°FMay 12May 7May 4May 2Apr 30Apr 28Apr 26Apr 24Apr 20
24°FApr 30Apr 26Apr 24Apr 21Apr 19Apr 17Apr 14Apr 10Apr 7
20°FApr 21Apr 17Apr 13Apr 10Apr 8Apr 7Apr 5Apr 3Apr 1
16°FApr 13Apr 9Apr 6Apr 4Apr 3Apr 1Mar 31Mar 28Mar 21

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°FSep 8Sep 12Sep 15Sep 18Sep 20Sep 23Sep 25Sep 29Oct 3
32°FSep 18Sep 22Sep 26Sep 29Oct 1Oct 3Oct 5Oct 9Oct 13
28°FSep 29Oct 2Oct 5Oct 8Oct 11Oct 14Oct 17Oct 22Oct 28
24°FOct 9Oct 14Oct 18Oct 22Oct 25Oct 29Nov 1Nov 4Nov 9
20°FOct 23Oct 28Nov 1Nov 4Nov 7Nov 9Nov 12Nov 16Nov 21
16°FNov 4Nov 9Nov 12Nov 15Nov 17Nov 20Nov 23Nov 27Dec 1

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°F136130126122119115112107102
32°F159153149145141138134129122
28°F183177172168164160156152146
24°F207201196193189185181177170
20°F228223219215211207204199193
16°F246240236233230226222218213

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
8,160
Cooling degree days, base 65°F
316
Growing degree days, base 40°F
3,832
Growing degree days, base 45°F
2,856
Growing degree days, base 50°F
2,016
Growing degree days, base 55°F
1,304
Growing degree days, base 60°F
731

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,51100
February1,32600
March1,15303
April713017
May3549160
June10951394
July22130573
August3694522
September21232284
October560158
November88505
December1,27900

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 10.4 km from Athens. 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 USC00173567 (Harmony). Public domain.