Huntsville climate

Huntsville Frost Dates and Growing Season

NOAA 1991-2020 normals for Huntsville Monastery, 5.3 km from Huntsville, elevation 5140 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Huntsville Monastery. 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 June 4 and the first fall freeze around September 16, a growing season of about 102 days.

Median at 32°F
last June 4, first September 16
Median at 28°F
last May 13, first September 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°F–––––––––
32°FJun 22Jun 16Jun 11Jun 8Jun 4Jun 1May 27May 22May 15
28°FJun 7Jun 1May 26May 18May 13May 9May 5May 2Apr 28
24°FMay 16May 7May 3Apr 29Apr 26Apr 22Apr 19Apr 15Apr 9
20°FApr 26Apr 20Apr 14Apr 10Apr 7Apr 3Mar 31Mar 27Mar 21
16°FApr 8Apr 3Mar 31Mar 28Mar 23Mar 19Mar 15Mar 11Mar 5

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°F–––––––––
32°FSep 1Sep 6Sep 10Sep 13Sep 16Sep 19Sep 22Sep 26Oct 1
28°FSep 12Sep 18Sep 21Sep 25Sep 28Oct 1Oct 3Oct 7Oct 12
24°FSep 23Sep 29Oct 3Oct 6Oct 10Oct 14Oct 18Oct 21Oct 25
20°FOct 5Oct 14Oct 18Oct 21Oct 24Oct 27Oct 30Nov 2Nov 8
16°FOct 19Oct 25Oct 29Nov 1Nov 3Nov 6Nov 10Nov 15Nov 21

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°F978882777268645950
32°F12411811210710297928678
28°F157149143138132126121115105
24°F188181175171166162156150140
20°F221213207202197192186180172
16°F248240234229224220215209202

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
7,210
Cooling degree days, base 65°F
338
Growing degree days, base 40°F
4,019
Growing degree days, base 45°F
2,966
Growing degree days, base 50°F
2,082
Growing degree days, base 55°F
1,352
Growing degree days, base 60°F
765

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,31600
February1,04200
March85002
April585033
May3373168
June12239370
July16156604
August23122564
September19017288
October551151
November90502
December1,27600

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 5.3 km from Huntsville. 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 USC00424135 (Huntsville Monastery). Public domain.