Blue Ridge climate

Blue Ridge Frost Dates and Growing Season

NOAA 1991-2020 normals for Blairsville Exp Stn, 34.7 km from Blue Ridge, elevation 1949 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Blairsville Exp Stn. 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 26 and the first fall freeze around October 19, a growing season of about 176 days.

Median at 36°F
last May 6, first October 11
Median at 32°F
last April 26, first October 19
Median at 28°F
last April 12, first October 28

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 19May 15May 12May 9May 6May 4May 1Apr 28Apr 22
32°FMay 11May 6May 2Apr 30Apr 26Apr 22Apr 18Apr 14Apr 8
28°FMay 1Apr 25Apr 19Apr 15Apr 12Apr 8Apr 4Mar 31Mar 25
24°FApr 17Apr 10Apr 5Apr 1Mar 30Mar 26Mar 21Mar 16Mar 7
20°FApr 2Mar 29Mar 24Mar 19Mar 14Mar 8Mar 3Feb 26Feb 16
16°FMar 21Mar 13Mar 7Mar 2Feb 25Feb 19Feb 12Feb 5Jan 30

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°FSep 30Oct 3Oct 6Oct 9Oct 11Oct 13Oct 15Oct 19Oct 25
32°FOct 7Oct 11Oct 14Oct 16Oct 19Oct 22Oct 25Oct 28Nov 1
28°FOct 15Oct 20Oct 23Oct 25Oct 28Oct 31Nov 2Nov 5Nov 10
24°FOct 25Oct 28Nov 1Nov 3Nov 7Nov 11Nov 14Nov 19Nov 26
20°FNov 4Nov 9Nov 14Nov 17Nov 21Nov 25Nov 29Dec 3Dec 11
16°FNov 14Nov 22Nov 28Dec 1Dec 5Dec 11Dec 22Dec 30Jan 5

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°F176170165161158154150145138
32°F198191186181176172167162155
28°F225215209204199195190184174
24°F253243236231225220214208199
20°F287275267260255249244237226
16°F321308301294288281273263254

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
100% 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
4,142
Cooling degree days, base 65°F
849
Growing degree days, base 40°F
6,278
Growing degree days, base 45°F
4,840
Growing degree days, base 50°F
3,577
Growing degree days, base 55°F
2,497
Growing degree days, base 60°F
1,588

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January856016
February687017
March555171
April3057193
May11050408
June13169606
July1263727
August1237701
September43109516
October27314236
November541163
December757024

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 34.7 km from Blue Ridge. 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 USC00090969 (Blairsville Exp Stn). Public domain.