Black Mountain climate

Black Mountain Frost Dates and Growing Season

NOAA 1991-2020 normals for N Fk 2, 5.4 km from Black Mountain, elevation 2480 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for N Fk 2. 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 5 and the first fall freeze around October 31, a growing season of about 206 days.

Median at 36°F
last April 21, first October 21
Median at 32°F
last April 5, first October 31
Median at 28°F
last March 24, first November 10

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

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 8Oct 12Oct 15Oct 18Oct 21Oct 23Oct 26Oct 29Nov 3
32°FOct 16Oct 21Oct 25Oct 28Oct 31Nov 2Nov 5Nov 9Nov 16
28°FOct 28Nov 1Nov 4Nov 7Nov 10Nov 13Nov 18Nov 23Nov 30
24°FNov 5Nov 10Nov 15Nov 19Nov 24Nov 29Dec 3Dec 7Dec 16
20°FNov 17Nov 26Dec 1Dec 5Dec 10Dec 16Dec 22Dec 29Jan 7
16°FDec 3Dec 9Dec 17Dec 23Dec 28Jan 1Jan 7Jan 13Jan 22

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°F203197191187183178173166159
32°F228221216211206203200195187
28°F258248242236231226221217208
24°F291280273266259254247242233
20°F323311304296290283275267256
16°F351338330323316308301294283

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
97% 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
4,001
Cooling degree days, base 65°F
805
Growing degree days, base 40°F
6,261
Growing degree days, base 45°F
4,782
Growing degree days, base 50°F
3,500
Growing degree days, base 55°F
2,430
Growing degree days, base 60°F
1,539

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January82808
February664011
March554062
April2807199
May9255430
June6163607
July0253718
August2217680
September5697490
October26013235
November524048
December735011

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 5.4 km from Black Mountain. 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 USC00316236 (N Fk 2). Public domain.