Fairfield County climate

Fairfield County Frost Dates and Growing Season

NOAA 1991-2020 normals for Winnsboro, 4.5 km from Fairfield County, elevation 530 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Winnsboro. 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 31 and the first fall freeze around November 6, a growing season of about 221 days.

Median at 36°F
last April 10, first October 28
Median at 32°F
last March 31, first November 6
Median at 28°F
last March 18, first November 17

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 1Apr 22Apr 17Apr 14Apr 10Apr 7Apr 4Apr 1Mar 28
32°FApr 18Apr 10Apr 6Apr 2Mar 31Mar 28Mar 24Mar 20Mar 14
28°FApr 4Mar 31Mar 26Mar 21Mar 18Mar 13Mar 8Mar 3Feb 26
24°FMar 23Mar 16Mar 11Mar 6Mar 2Feb 26Feb 20Feb 11Jan 31
20°FMar 10Mar 3Feb 27Feb 18Feb 11Feb 4Jan 31Jan 24Jan 12
16°FFeb 28Feb 13Feb 6Feb 1Jan 29Jan 23Jan 18Jan 11Jan 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 14Oct 19Oct 23Oct 25Oct 28Oct 30Nov 1Nov 6Nov 11
32°FOct 25Oct 29Nov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 21
28°FNov 2Nov 6Nov 10Nov 14Nov 17Nov 21Nov 26Dec 1Dec 8
24°FNov 13Nov 18Nov 24Nov 30Dec 3Dec 8Dec 16Dec 26Jan 4
20°FNov 30Dec 5Dec 12Dec 20Dec 27Jan 1Jan 6Jan 12Jan 21
16°FDec 12Dec 23Dec 29Jan 2Jan 7Jan 13Jan 18Jan 24Feb 3

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°F219212207203199195190185177
32°F246238231226221216211205200
28°F276266259253247242237230220
24°F311300292285279272265257247
20°F350337331322312305298290276
16°F365365357349341334326315303

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
96% of years
16°F or colder
76% 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
3,107
Cooling degree days, base 65°F
1,750
Growing degree days, base 40°F
7,970
Growing degree days, base 45°F
6,410
Growing degree days, base 50°F
5,004
Growing degree days, base 55°F
3,757
Growing degree days, base 60°F
2,670

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January713036
February554150
March40310159
April16750345
May41165589
June3345792
July0465930
August0414879
September14241676
October15253374
November4216124
December638150

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 4.5 km from Fairfield 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 USC00389327 (Winnsboro). Public domain.