Colleton County climate

Colleton County Frost Dates and Growing Season

NOAA 1991-2020 normals for Walterboro 1 Sw, 5.3 km from Colleton County, elevation 56 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Walterboro 1 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 March 19 and the first fall freeze around November 12, a growing season of about 239 days.

Median at 36°F
last April 2, first November 1
Median at 32°F
last March 19, first November 12
Median at 28°F
last March 1, first November 28

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 21Apr 15Apr 10Apr 6Apr 2Mar 30Mar 25Mar 20Mar 12
32°FApr 9Apr 1Mar 27Mar 23Mar 19Mar 15Mar 9Mar 3Feb 24
28°FMar 25Mar 17Mar 11Mar 5Mar 1Feb 26Feb 21Feb 15Feb 7
24°FMar 12Mar 3Feb 25Feb 19Feb 12Feb 5Feb 1Jan 28Jan 18
20°FFeb 28Feb 17Feb 9Feb 2Jan 30Jan 25Jan 18Jan 12Jan 1
16°FFeb 11Feb 5Jan 31Jan 29Jan 24Jan 19Jan 14Jan 9Jan 1

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 24Oct 27Oct 30Nov 1Nov 4Nov 6Nov 10Nov 16
32°FOct 29Nov 2Nov 5Nov 8Nov 12Nov 16Nov 19Nov 24Dec 1
28°FNov 6Nov 13Nov 18Nov 23Nov 28Dec 1Dec 6Dec 15Dec 29
24°FNov 20Dec 1Dec 5Dec 12Dec 21Dec 30Jan 4Jan 10Jan 21
20°FDec 8Dec 20Dec 29Jan 2Jan 6Jan 11Jan 17Jan 26Feb 7
16°FDec 25Jan 1Jan 7Jan 13Jan 16Jan 20Jan 27Jan 31Feb 7

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°F238229224218213208203197188
32°F266256251244239233226220210
28°F307296286279271264258251239
24°F341331323315308302294284272
20°F365365357347338333326315304
16°F365365365365365365357342329

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
96% of years
20°F or colder
76% of years
16°F or colder
34% 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
2,322
Cooling degree days, base 65°F
2,016
Growing degree days, base 40°F
8,893
Growing degree days, base 45°F
7,205
Growing degree days, base 50°F
5,657
Growing degree days, base 55°F
4,271
Growing degree days, base 60°F
3,050

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January571278
February428393
March28419239
April11663401
May21213657
June0375825
July0490955
August0449914
September5293738
October9890462
November31616191
December4844104

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 5.3 km from Colleton 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 USC00388922 (Walterboro 1 Sw). Public domain.