Henry County climate

Henry County Frost Dates and Growing Season

NOAA 1991-2020 normals for Mt Pleasant 1 Ssw, 4.7 km from Henry County, elevation 730 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mt Pleasant 1 Ssw. 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 30 and the first fall freeze around October 10, a growing season of about 163 days.

Median at 36°F
last May 9, first October 1
Median at 32°F
last April 30, first October 10
Median at 28°F
last April 17, first October 20

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 23May 19May 15May 12May 9May 6May 3Apr 30Apr 25
32°FMay 14May 9May 6May 3Apr 30Apr 27Apr 22Apr 18Apr 13
28°FMay 5Apr 30Apr 25Apr 20Apr 17Apr 14Apr 10Apr 7Apr 3
24°FApr 23Apr 15Apr 12Apr 8Apr 5Apr 3Mar 31Mar 28Mar 22
20°FApr 9Apr 4Apr 1Mar 30Mar 27Mar 23Mar 20Mar 14Mar 7
16°FApr 1Mar 28Mar 24Mar 20Mar 17Mar 14Mar 10Mar 6Feb 28

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 16Sep 21Sep 24Sep 27Oct 1Oct 3Oct 5Oct 8Oct 13
32°FSep 24Sep 29Oct 3Oct 7Oct 10Oct 12Oct 15Oct 18Oct 23
28°FOct 3Oct 10Oct 14Oct 17Oct 20Oct 23Oct 26Oct 29Nov 2
24°FOct 16Oct 22Oct 26Oct 28Oct 31Nov 1Nov 4Nov 8Nov 13
20°FOct 27Nov 1Nov 3Nov 6Nov 9Nov 11Nov 15Nov 19Nov 25
16°FNov 3Nov 7Nov 11Nov 15Nov 18Nov 21Nov 25Nov 29Dec 4

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°F163156152148144140136132125
32°F183175171166163159155149142
28°F204197193189185180175170163
24°F226218214209206202198192185
20°F248239234229225221217213206
16°F268261255250245240236230224

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
6,380
Cooling degree days, base 65°F
814
Growing degree days, base 40°F
5,284
Growing degree days, base 45°F
4,140
Growing degree days, base 50°F
3,118
Growing degree days, base 55°F
2,215
Growing degree days, base 60°F
1,444

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33400
February1,07703
March835132
April4537121
May18848338
June27165588
July4267728
August11220674
September10893439
October40312163
November779029
December1,16202

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 Henry 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 USC00135796 (Mt Pleasant 1 Ssw). Public domain.