Jefferson Davis County climate

Jefferson Davis County Frost Dates and Growing Season

NOAA 1991-2020 normals for Collins, 26.4 km from Jefferson Davis County, elevation 290 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Collins. 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 17 and the first fall freeze around November 12, a growing season of about 238 days.

Median at 36°F
last April 1, first November 2
Median at 32°F
last March 17, first November 12
Median at 28°F
last March 4, first November 26

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 16Apr 11Apr 7Apr 4Apr 1Mar 29Mar 25Mar 19Mar 13
32°FApr 4Mar 30Mar 25Mar 21Mar 17Mar 13Mar 9Mar 5Feb 28
28°FMar 22Mar 17Mar 12Mar 8Mar 4Mar 1Feb 26Feb 19Feb 6
24°FMar 15Mar 6Feb 28Feb 25Feb 18Feb 12Feb 5Jan 31Jan 22
20°FMar 3Feb 24Feb 14Feb 7Feb 2Jan 30Jan 23Jan 14Jan 5
16°FFeb 24Feb 12Feb 4Jan 31Jan 25Jan 20Jan 12Jan 6Dec 29

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 28Oct 31Nov 2Nov 5Nov 8Nov 12Nov 20
32°FOct 30Nov 2Nov 5Nov 8Nov 12Nov 16Nov 20Nov 25Dec 1
28°FNov 6Nov 12Nov 17Nov 22Nov 26Nov 30Dec 3Dec 7Dec 17
24°FNov 20Nov 28Dec 2Dec 6Dec 12Dec 21Dec 28Jan 3Jan 12
20°FDec 4Dec 14Dec 24Dec 29Jan 2Jan 6Jan 10Jan 17Feb 1
16°FDec 16Dec 26Jan 1Jan 5Jan 9Jan 14Jan 20Jan 27Feb 6

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°F240230225219215211207202194
32°F263255249243238233228223215
28°F296284276270263258253248240
24°F334321312305299292282274263
20°F365355343335330321313306294
16°F365365365365363349339332318

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
99% of years
20°F or colder
87% of years
16°F or colder
55% 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
2,046
Cooling degree days, base 65°F
2,448
Growing degree days, base 40°F
9,595
Growing degree days, base 45°F
7,884
Growing degree days, base 50°F
6,289
Growing degree days, base 55°F
4,842
Growing degree days, base 60°F
3,558

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January534493
February36710139
March23634289
April83106475
May10271725
June0442892
July05351,000
August0518983
September2362810
October74134528
November27323230
December46811126

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 26.4 km from Jefferson Davis 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 USC00221852 (Collins). Public domain.