Blue Ridge climate

Blue Ridge Frost Dates and Growing Season

NOAA 1991-2020 normals for Milstead, 28.8 km from Blue Ridge, elevation 215 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Milstead. 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 25 and the first fall freeze around November 8, a growing season of about 228 days.

Median at 36°F
last April 6, first October 30
Median at 32°F
last March 25, first November 8
Median at 28°F
last March 10, first November 21

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

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

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°F230221215210206202197192185
32°F254245239233228224218212205
28°F287275267261255249244236227
24°F326309302295288280272265255
20°F365350339332325317309301287
16°F365365365365362352341332321

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
99% of years
20°F or colder
89% of years
16°F or colder
49% 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
2,551
Cooling degree days, base 65°F
1,942
Growing degree days, base 40°F
8,624
Growing degree days, base 45°F
6,971
Growing degree days, base 50°F
5,465
Growing degree days, base 55°F
4,123
Growing degree days, base 60°F
2,946

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January612163
February462281
March31612207
April13553375
May24197639
June0365814
July0470935
August0448913
September4293739
October10586452
November34812170
December547379

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 28.8 km from Blue Ridge. 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 USC00015439 (Milstead). Public domain.