Madison County climate

Madison County Frost Dates and Growing Season

NOAA 1991-2020 normals for Huntsville 1 Ssw, 7 km from Madison County, elevation 1783 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Huntsville 1 Ssw. 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 30 and the first fall freeze around November 7, a growing season of about 224 days.

Median at 36°F
last April 10, first October 28
Median at 32°F
last March 30, first November 7
Median at 28°F
last March 18, first November 17

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 27Apr 22Apr 18Apr 14Apr 10Apr 7Apr 4Mar 31Mar 25
32°FApr 15Apr 8Apr 5Apr 1Mar 30Mar 26Mar 22Mar 17Mar 11
28°FApr 4Mar 31Mar 26Mar 22Mar 18Mar 14Mar 9Mar 4Feb 27
24°FMar 26Mar 19Mar 15Mar 11Mar 7Mar 3Feb 28Feb 23Feb 16
20°FMar 16Mar 10Mar 5Mar 2Feb 27Feb 21Feb 17Feb 9Jan 30
16°FMar 10Mar 3Feb 28Feb 21Feb 16Feb 8Feb 1Jan 26Jan 14

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 14Oct 20Oct 23Oct 25Oct 28Oct 31Nov 2Nov 5Nov 10
32°FOct 24Oct 29Nov 1Nov 4Nov 7Nov 10Nov 14Nov 17Nov 23
28°FNov 1Nov 5Nov 10Nov 13Nov 17Nov 21Nov 24Nov 29Dec 4
24°FNov 9Nov 16Nov 20Nov 24Nov 27Dec 1Dec 6Dec 10Dec 18
20°FNov 19Nov 25Nov 29Dec 3Dec 8Dec 13Dec 18Dec 23Jan 1
16°FNov 29Dec 6Dec 12Dec 17Dec 22Dec 27Jan 1Jan 7Jan 17

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°F224215209205201197192187179
32°F247239234229224219213208201
28°F270260254250245240235228219
24°F293283276270265260255249241
20°F319309300294288282275268257
16°F342332322315309304297289279

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
99% 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
3,659
Cooling degree days, base 65°F
1,541
Growing degree days, base 40°F
7,449
Growing degree days, base 45°F
5,970
Growing degree days, base 50°F
4,633
Growing degree days, base 55°F
3,448
Growing degree days, base 60°F
2,411

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January831025
February646037
March4708134
April20736302
May61117521
June4292738
July0428893
August1406869
September26205629
October18446344
November4774112
December754030

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 7 km from Madison 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 USC00033544 (Huntsville 1 Ssw). Public domain.