Walker County climate

Walker County Frost Dates and Growing Season

NOAA 1991-2020 normals for Huntsville, 4.6 km from Walker County, elevation 494 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Huntsville. 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 1 and the first fall freeze around November 28, a growing season of about 272 days.

Median at 36°F
last March 14, first November 16
Median at 32°F
last March 1, first November 28
Median at 28°F
last February 12, first December 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°FApr 3Mar 28Mar 22Mar 18Mar 14Mar 9Mar 4Feb 28Feb 21
32°FMar 22Mar 15Mar 10Mar 4Mar 1Feb 25Feb 19Feb 13Feb 2
28°FMar 11Mar 4Feb 26Feb 19Feb 12Feb 4Jan 31Jan 24Jan 13
24°FMar 2Feb 21Feb 10Feb 2Jan 29Jan 23Jan 16Jan 7Dec 27
20°FFeb 21Feb 8Feb 1Jan 29Jan 20Jan 14Jan 7Jan 3Dec 27
16°FFeb 14Feb 8Feb 4Feb 2Jan 29Jan 16Jan 9Jan 7Jan 3

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

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°F276266259254248243237230221
32°F308294286279272266260253242
28°F344331322312304298291280267
24°F365365357348339331320310300
20°F365365365365365365355341326
16°F365365365365365365365365359

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
98% of years
24°F or colder
78% of years
20°F or colder
40% of years
16°F or colder
12% 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
1,941
Cooling degree days, base 65°F
2,516
Growing degree days, base 40°F
9,779
Growing degree days, base 45°F
8,070
Growing degree days, base 50°F
6,465
Growing degree days, base 55°F
4,991
Growing degree days, base 60°F
3,669

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January5125107
February36010149
March22035309
April73106486
May10272727
June0440889
July05381,003
August05411,006
September3369816
October59160568
November25034272
December4579132

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 4.6 km from Walker County. 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 USC00414382 (Huntsville). Public domain.