Alamance climate

Alamance Frost Dates and Growing Season

NOAA 1991-2020 normals for Burlington Alamance AP, 1.5 km from Alamance, elevation 617 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Burlington Alamance AP. 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 1 and the first fall freeze around November 2, a growing season of about 215 days.

Median at 36°F
last April 14, first October 25
Median at 32°F
last April 1, first November 2
Median at 28°F
last March 18, first November 13

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 3Apr 26Apr 21Apr 17Apr 14Apr 11Apr 7Apr 4Mar 31
32°FApr 17Apr 12Apr 7Apr 4Apr 1Mar 28Mar 24Mar 19Mar 13
28°FApr 3Mar 30Mar 25Mar 21Mar 18Mar 15Mar 11Mar 7Mar 1
24°FMar 22Mar 18Mar 14Mar 10Mar 5Mar 1Feb 26Feb 21Feb 11
20°FMar 13Mar 7Mar 2Feb 27Feb 22Feb 16Feb 8Feb 1Jan 22
16°FMar 1Feb 23Feb 15Feb 6Feb 1Jan 29Jan 23Jan 17Jan 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 13Oct 17Oct 21Oct 23Oct 25Oct 27Oct 30Nov 1Nov 5
32°FOct 21Oct 26Oct 29Nov 1Nov 2Nov 5Nov 7Nov 11Nov 16
28°FNov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 19Nov 23Nov 30
24°FNov 9Nov 14Nov 17Nov 21Nov 26Nov 30Dec 3Dec 9Dec 20
20°FNov 21Nov 28Dec 3Dec 8Dec 13Dec 20Dec 28Jan 4Jan 15
16°FDec 6Dec 15Dec 25Jan 1Jan 5Jan 10Jan 16Jan 23Feb 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°F211205200197192188183178171
32°F237229224220215211207202194
28°F262254248243239235231226219
24°F297286277270265260255248240
20°F331320311303297290282275266
16°F365356345336332325316308299

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
99% 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
3,268
Cooling degree days, base 65°F
1,737
Growing degree days, base 40°F
7,840
Growing degree days, base 45°F
6,302
Growing degree days, base 50°F
4,922
Growing degree days, base 55°F
3,701
Growing degree days, base 60°F
2,638

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January746133
February584249
March43010142
April17951336
May45160580
June1342790
July0470935
August0419883
September16230664
October17048352
November4364111
December661248

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 1.5 km from Alamance. 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 USW00093783 (Burlington Alamance AP). Public domain.