Charleston climate

Charleston Frost Dates and Growing Season

NOAA 1991-2020 normals for Cleveland Fltr Plt, 8.1 km from Charleston, elevation 842 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cleveland Fltr Plt. 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 6 and the first fall freeze around October 30, a growing season of about 206 days.

Median at 36°F
last April 19, first October 22
Median at 32°F
last April 6, first October 30
Median at 28°F
last March 26, first November 8

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°FMay 4Apr 29Apr 25Apr 21Apr 19Apr 16Apr 13Apr 9Apr 3
32°FApr 21Apr 16Apr 12Apr 9Apr 6Apr 3Mar 31Mar 27Mar 20
28°FApr 10Apr 5Apr 2Mar 29Mar 26Mar 22Mar 18Mar 13Mar 6
24°FMar 31Mar 26Mar 20Mar 16Mar 12Mar 8Mar 3Feb 26Feb 18
20°FMar 21Mar 13Mar 6Mar 2Feb 25Feb 18Feb 13Feb 6Jan 29
16°FMar 7Feb 28Feb 19Feb 12Feb 6Feb 1Jan 28Jan 20Jan 8

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 8Oct 13Oct 16Oct 19Oct 22Oct 24Oct 26Oct 29Nov 2
32°FOct 18Oct 22Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 11
28°FOct 25Oct 31Nov 2Nov 5Nov 8Nov 10Nov 14Nov 19Nov 25
24°FNov 5Nov 9Nov 13Nov 16Nov 21Nov 25Nov 29Dec 3Dec 13
20°FNov 13Nov 21Nov 27Dec 1Dec 5Dec 11Dec 19Dec 27Jan 2
16°FNov 29Dec 7Dec 17Dec 25Dec 30Jan 2Jan 6Jan 12Jan 24

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°F207200195190186181177172165
32°F228221215210206202197192186
28°F254246240234228224218211205
24°F286275268262256250245238230
20°F321310301294287280273265255
16°F353340332326320314306297286

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
100% of years
16°F or colder
96% 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
3,474
Cooling degree days, base 65°F
1,542
Growing degree days, base 40°F
7,498
Growing degree days, base 45°F
5,990
Growing degree days, base 50°F
4,636
Growing degree days, base 55°F
3,445
Growing degree days, base 60°F
2,417

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January784026
February600140
March4486128
April19834303
May54133545
June3304751
July0415880
August0391856
September17214647
October18640333
November483491
December702136

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 8.1 km from Charleston. 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 USC00401808 (Cleveland Fltr Plt). Public domain.