Harrison County climate

Harrison County Frost Dates and Growing Season

NOAA 1991-2020 normals for Gulfport - Biloxi AP, 0.5 km from Harrison County, elevation 42 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Gulfport - Biloxi AP. 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 February 23 and the first fall freeze around December 3, a growing season of about 287 days.

Median at 36°F
last March 9, first November 18
Median at 32°F
last February 23, first December 3
Median at 28°F
last February 1, first December 31

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°FMar 30Mar 23Mar 18Mar 14Mar 9Mar 5Feb 28Feb 24Feb 16
32°FMar 16Mar 11Mar 5Feb 28Feb 23Feb 17Feb 9Feb 3Jan 25
28°FMar 5Feb 25Feb 15Feb 6Feb 1Jan 28Jan 22Jan 15Jan 5
24°FFeb 24Feb 7Feb 1Jan 28Jan 24Jan 17Jan 10Jan 4Dec 29
20°FFeb 2Jan 29Jan 26Jan 20Jan 14Jan 11Jan 6Jan 2Jan 1
16°F–––––––––

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°FNov 3Nov 7Nov 12Nov 16Nov 18Nov 22Nov 26Dec 1Dec 7
32°FNov 12Nov 19Nov 25Dec 1Dec 3Dec 9Dec 16Dec 28Jan 5
28°FNov 28Dec 5Dec 13Dec 23Dec 31Jan 2Jan 7Jan 14Jan 23
24°FDec 12Dec 27Jan 1Jan 3Jan 7Jan 12Jan 18Jan 26Feb 5
20°FDec 30Jan 1Jan 3Jan 6Jan 11Jan 14Jan 21Jan 27Feb 1
16°F–––––––––

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°F284274267261255251245238228
32°F323311301294287280273264255
28°F359345337331323314306297286
24°F365365365365356348339332317
20°F365365365365365365365365346
16°F365365365365365365365365365

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
91% of years
24°F or colder
60% of years
20°F or colder
20% of years
16°F or colder
4% 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
1,507
Cooling degree days, base 65°F
2,749
Growing degree days, base 40°F
10,387
Growing degree days, base 45°F
8,615
Growing degree days, base 50°F
6,931
Growing degree days, base 55°F
5,380
Growing degree days, base 60°F
3,979

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4168149
February28216194
March16645352
April48122524
May3313775
June0478928
July05471,012
August05471,012
September1426876
October39194620
November19836303
December35515185

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 0.5 km from Harrison 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 USW00093874 (Gulfport - Biloxi AP). Public domain.