Alcorn County climate

Alcorn County Frost Dates and Growing Season

NOAA 1991-2020 normals for Corinth 7 Sw, 3.5 km from Alcorn County, elevation 385 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Corinth 7 Sw. 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 2 and the first fall freeze around November 1, a growing season of about 213 days.

Median at 36°F
last April 11, first October 24
Median at 32°F
last April 2, first November 1
Median at 28°F
last March 20, first November 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°FApr 27Apr 21Apr 18Apr 14Apr 11Apr 8Apr 5Apr 2Mar 29
32°FApr 17Apr 11Apr 7Apr 4Apr 2Mar 30Mar 26Mar 22Mar 16
28°FApr 6Apr 1Mar 28Mar 25Mar 20Mar 16Mar 12Mar 5Feb 26
24°FMar 24Mar 18Mar 14Mar 9Mar 4Feb 28Feb 24Feb 18Feb 8
20°FMar 15Mar 5Feb 28Feb 23Feb 17Feb 11Feb 4Jan 30Jan 19
16°FMar 1Feb 19Feb 12Feb 4Jan 31Jan 27Jan 20Jan 11Dec 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 11Oct 16Oct 19Oct 22Oct 24Oct 26Oct 29Nov 1Nov 4
32°FOct 20Oct 24Oct 27Oct 30Nov 1Nov 3Nov 5Nov 9Nov 15
28°FOct 30Nov 2Nov 5Nov 8Nov 11Nov 15Nov 19Nov 24Dec 1
24°FNov 5Nov 9Nov 14Nov 18Nov 23Nov 28Dec 1Dec 6Dec 19
20°FNov 13Nov 23Dec 1Dec 4Dec 9Dec 17Dec 25Jan 1Jan 11
16°FDec 2Dec 9Dec 21Dec 27Jan 1Jan 4Jan 10Jan 18Feb 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°F213207202197193190185181174
32°F235227221217213208205200194
28°F264253247242237231225219212
24°F296283275269263258252245236
20°F331319310303296288281272258
16°F365352342335330323312305294

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
99% of years
16°F or colder
89% 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
3,392
Cooling degree days, base 65°F
1,771
Growing degree days, base 40°F
7,839
Growing degree days, base 45°F
6,330
Growing degree days, base 50°F
4,963
Growing degree days, base 55°F
3,743
Growing degree days, base 60°F
2,680

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January782132
February596151
March4269153
April18247332
May42173595
June1345793
July0460925
August0430894
September18243675
October18257356
November4685110
December694148

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 3.5 km from Alcorn 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 USC00221962 (Corinth 7 Sw). Public domain.