Houston climate

Houston Frost Dates and Growing Season

NOAA 1991-2020 normals for Houston, 1.9 km from Houston, elevation 290 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Houston. 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 28 and the first fall freeze around November 1, a growing season of about 220 days.

Median at 36°F
last April 9, first October 24
Median at 32°F
last March 28, first November 1
Median at 28°F
last March 12, first November 14

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 19Apr 15Apr 12Apr 9Apr 6Apr 3Mar 30Mar 22
32°FApr 15Apr 9Apr 5Apr 1Mar 28Mar 23Mar 19Mar 13Mar 6
28°FApr 4Mar 28Mar 22Mar 17Mar 12Mar 8Mar 3Feb 27Feb 21
24°FMar 17Mar 11Mar 5Mar 1Feb 26Feb 21Feb 16Feb 10Feb 2
20°FMar 4Feb 26Feb 20Feb 14Feb 8Feb 3Jan 31Jan 24Jan 14
16°FFeb 21Feb 10Feb 3Jan 31Jan 28Jan 22Jan 18Jan 11Dec 29

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 10Oct 14Oct 18Oct 21Oct 24Oct 26Oct 29Nov 1Nov 6
32°FOct 19Oct 24Oct 27Oct 31Nov 1Nov 5Nov 9Nov 14Nov 21
28°FOct 28Nov 1Nov 5Nov 9Nov 14Nov 18Nov 23Nov 29Dec 4
24°FNov 5Nov 12Nov 18Nov 24Nov 29Dec 3Dec 7Dec 15Dec 27
20°FNov 18Nov 30Dec 5Dec 11Dec 18Dec 25Jan 1Jan 5Jan 15
16°FDec 5Dec 14Dec 25Dec 30Jan 2Jan 6Jan 12Jan 19Feb 1

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°F221214207202198194191186179
32°F244236230225220215210204196
28°F276266258252247241234229219
24°F309298289283277271264255247
20°F346332324317310304297288275
16°F365365356346338334327318306

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
97% of years
16°F or colder
78% 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
2,913
Cooling degree days, base 65°F
1,964
Growing degree days, base 40°F
8,397
Growing degree days, base 45°F
6,814
Growing degree days, base 50°F
5,374
Growing degree days, base 55°F
4,078
Growing degree days, base 60°F
2,938

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January700148
February526371
March33916208
April15058371
May31196631
June1381831
July0473938
August0453918
September13289726
October14382416
November39411155
December618263

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 1.9 km from Houston. 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 USC00224265 (Houston). Public domain.