Simpsonville climate

Simpsonville Frost Dates and Growing Season

NOAA 1991-2020 normals for Fountain Inn 2 Sw, 7.4 km from Simpsonville, elevation 830 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fountain Inn 2 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 29 and the first fall freeze around November 5, a growing season of about 222 days.

Median at 36°F
last April 11, first October 26
Median at 32°F
last March 29, first November 5
Median at 28°F
last March 15, 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°FApr 30Apr 22Apr 18Apr 15Apr 11Apr 8Apr 5Apr 1Mar 26
32°FApr 14Apr 8Apr 4Apr 1Mar 29Mar 25Mar 21Mar 17Mar 10
28°FMar 31Mar 26Mar 21Mar 18Mar 15Mar 10Mar 6Feb 28Feb 21
24°FMar 21Mar 16Mar 11Mar 6Mar 1Feb 25Feb 19Feb 8Jan 31
20°FMar 14Mar 4Feb 26Feb 17Feb 8Feb 2Jan 29Jan 20Jan 11
16°FFeb 28Feb 18Feb 6Jan 31Jan 26Jan 20Jan 16Jan 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 14Oct 18Oct 21Oct 24Oct 26Oct 29Nov 1Nov 3Nov 7
32°FOct 24Oct 28Oct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 20
28°FNov 2Nov 7Nov 11Nov 14Nov 17Nov 21Nov 26Dec 1Dec 6
24°FNov 15Nov 20Nov 26Nov 29Dec 3Dec 7Dec 12Dec 20Dec 30
20°FNov 29Dec 4Dec 10Dec 17Dec 24Dec 30Jan 3Jan 9Jan 18
16°FDec 8Dec 20Dec 28Jan 2Jan 6Jan 11Jan 16Jan 21Feb 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°F217211206201197193188182174
32°F245237231227222217213208200
28°F277268261255250245240235227
24°F313301292284278272264258251
20°F345334326317309302294286276
16°F365363353346339333325316301

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
97% of years
16°F or colder
79% 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
3,210
Cooling degree days, base 65°F
1,603
Growing degree days, base 40°F
7,731
Growing degree days, base 45°F
6,164
Growing degree days, base 50°F
4,750
Growing degree days, base 55°F
3,513
Growing degree days, base 60°F
2,469

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January727029
February559053
March4205140
April18133311
May51140554
June2315763
July0435900
August0397862
September21229658
October16845349
November434397
December648034

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 7.4 km from Simpsonville. 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 USC00383145 (Fountain Inn 2 Sw). Public domain.