Houston climate

Houston Frost Dates and Growing Season

NOAA 1991-2020 normals for Anderson Lake, 25.3 km from Houston, elevation 458 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Anderson Lake. 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 May 16 and the first fall freeze around September 23, a growing season of about 128 days.

Median at 36°F
last June 1, first September 10
Median at 32°F
last May 16, first September 23
Median at 28°F
last May 1, first October 3

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°FJun 10Jun 7Jun 5Jun 3Jun 1May 30May 27May 24May 19
32°FMay 31May 26May 23May 20May 16May 13May 10May 6May 1
28°FMay 16May 11May 6May 3May 1Apr 29Apr 25Apr 20Apr 15
24°FMay 1Apr 27Apr 23Apr 19Apr 16Apr 13Apr 10Apr 6Apr 3
20°FApr 22Apr 17Apr 12Apr 9Apr 6Apr 4Apr 2Mar 31Mar 24
16°FApr 17Apr 11Apr 7Apr 4Apr 2Mar 31Mar 27Mar 21Mar 15

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°FAug 28Sep 1Sep 4Sep 6Sep 10Sep 13Sep 16Sep 19Sep 23
32°FSep 8Sep 13Sep 16Sep 20Sep 23Sep 25Sep 27Sep 30Oct 5
28°FSep 19Sep 24Sep 28Oct 1Oct 3Oct 7Oct 10Oct 13Oct 18
24°FOct 1Oct 4Oct 8Oct 11Oct 14Oct 17Oct 20Oct 24Oct 28
20°FOct 8Oct 14Oct 17Oct 20Oct 23Oct 25Oct 28Nov 1Nov 6
16°FOct 15Oct 20Oct 24Oct 27Oct 29Nov 1Nov 4Nov 8Nov 14

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°F11811210710410097938981
32°F149141136132128124120114108
28°F177169165160156151147142135
24°F200194189184180176171166159
20°F217210206202198194190184178
16°F232225218214210206203198192

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
10,197
Cooling degree days, base 65°F
5
Growing degree days, base 40°F
2,045
Growing degree days, base 45°F
1,255
Growing degree days, base 50°F
637
Growing degree days, base 55°F
232
Growing degree days, base 60°F
51

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,47900
February1,21700
March1,20400
April81902
May533037
June3191143
July2134256
August3010170
September539027
October90802
November1,25400
December1,41200

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 25.3 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 USC00500302 (Anderson Lake). Public domain.