Sheffield climate

Sheffield Frost Dates and Growing Season

NOAA 1991-2020 normals for Muscle Shoals Wtp, 5.3 km from Sheffield, elevation 540 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Muscle Shoals Wtp. 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 30 and the first fall freeze around November 3, a growing season of about 220 days.

Median at 36°F
last April 10, first October 26
Median at 32°F
last March 30, first November 3
Median at 28°F
last March 17, first November 14

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

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

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°F219212208203199196192187181
32°F242235229224220215211206200
28°F269259252247242238233227220
24°F299286280274267261256250241
20°F333321311305299293286278267
16°F365352343335330322315308297

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
98% of years
16°F or colder
87% 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
3,311
Cooling degree days, base 65°F
1,769
Growing degree days, base 40°F
7,886
Growing degree days, base 45°F
6,356
Growing degree days, base 50°F
4,967
Growing degree days, base 55°F
3,737
Growing degree days, base 60°F
2,675

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January772030
February600144
March4197151
April17941324
May44159580
June0347796
July0456921
August0437902
September12258696
October15860377
November4454105
December682042

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 Sheffield. 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 USC00015751 (Muscle Shoals Wtp). Public domain.