Warren County climate

Warren County Frost Dates and Growing Season

NOAA 1991-2020 normals for Vicksburg City, 3.8 km from Warren County, elevation 80 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Vicksburg City. 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 26 and the first fall freeze around November 22, a growing season of about 269 days.

Median at 36°F
last March 9, first November 9
Median at 32°F
last February 26, first November 22
Median at 28°F
last February 8, first December 4

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 28Mar 21Mar 16Mar 12Mar 9Mar 5Feb 28Feb 25Feb 19
32°FMar 16Mar 9Mar 5Mar 1Feb 26Feb 22Feb 16Feb 9Jan 31
28°FMar 6Feb 28Feb 22Feb 14Feb 8Feb 2Jan 30Jan 23Jan 11
24°FFeb 22Feb 9Feb 3Jan 31Jan 26Jan 22Jan 14Jan 4Dec 22
20°FFeb 8Feb 1Jan 29Jan 25Jan 19Jan 14Jan 7Dec 31Dec 16
16°FFeb 6Jan 31Jan 27Jan 23Jan 20Jan 15Jan 13Jan 9Jan 2

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 27Nov 1Nov 3Nov 6Nov 9Nov 13Nov 17Nov 24Dec 1
32°FNov 3Nov 7Nov 12Nov 17Nov 22Nov 26Dec 1Dec 6Dec 15
28°FNov 11Nov 18Nov 25Nov 30Dec 4Dec 9Dec 19Dec 31Jan 8
24°FNov 25Dec 2Dec 10Dec 17Dec 26Jan 1Jan 6Jan 13Jan 23
20°FDec 6Dec 18Dec 28Jan 1Jan 5Jan 10Jan 14Jan 21Feb 1
16°FJan 1Jan 2Jan 7Jan 10Jan 13Jan 15Jan 21Jan 27Feb 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°F273263256250246242235228220
32°F303291282275269263257251243
28°F335324313304297290282273262
24°F365360349340334327319307295
20°F365365365365365358349339329
16°F365365365365365365365365351

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
98% of years
24°F or colder
84% of years
20°F or colder
48% of years
16°F or colder
18% 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
2,078
Cooling degree days, base 65°F
2,586
Growing degree days, base 40°F
9,733
Growing degree days, base 45°F
8,046
Growing degree days, base 50°F
6,471
Growing degree days, base 55°F
5,024
Growing degree days, base 60°F
3,719

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January5385105
February39010139
March22440309
April70112494
May10297752
June0471921
July05501,015
August05501,015
September2370817
October74141533
November28529240
December48512131

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 3.8 km from Warren County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00229230 (Vicksburg City). Public domain.