Brenham climate

Brenham Frost Dates and Growing Season

NOAA 1991-2020 normals for Brenham, 0.9 km from Brenham, elevation 313 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Brenham. 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 2 and the first fall freeze around November 30, a growing season of about 273 days.

Median at 36°F
last March 13, first November 17
Median at 32°F
last March 2, first November 30
Median at 28°F
last February 10, first December 18

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 1Mar 27Mar 21Mar 17Mar 13Mar 9Mar 5Mar 1Feb 23
32°FMar 20Mar 14Mar 9Mar 5Mar 2Feb 27Feb 19Feb 12Jan 31
28°FMar 11Mar 4Feb 27Feb 19Feb 10Feb 2Jan 28Jan 20Jan 6
24°FMar 3Feb 20Feb 6Jan 31Jan 25Jan 19Jan 10Jan 2Dec 21
20°FFeb 7Feb 1Jan 23Jan 19Jan 14Jan 8Jan 4Dec 31Dec 18
16°F–––––––––

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 13Nov 17Nov 21Nov 26Dec 1Dec 5
32°FNov 8Nov 15Nov 21Nov 26Nov 30Dec 3Dec 8Dec 14Dec 23
28°FNov 18Nov 28Dec 4Dec 9Dec 18Dec 25Jan 1Jan 6Jan 19
24°FDec 4Dec 12Dec 22Dec 30Jan 3Jan 7Jan 14Jan 20Feb 4
20°FDec 13Dec 24Dec 31Jan 3Jan 8Jan 11Jan 18Jan 24Feb 2
16°F–––––––––

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°F274266260255249243237230222
32°F306294286280273268261254242
28°F344333324315307300292283268
24°F365365363354345336330318302
20°F365365365365365365365355340
16°F365365365365365365365365365

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
96% of years
24°F or colder
67% of years
20°F or colder
27% of years
16°F or colder
5% 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
1,738
Cooling degree days, base 65°F
2,852
Growing degree days, base 40°F
10,288
Growing degree days, base 45°F
8,552
Growing degree days, base 50°F
6,914
Growing degree days, base 55°F
5,403
Growing degree days, base 60°F
4,045

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4678123
February33014167
March19645335
April55126522
May5312772
June0487937
July05811,046
August06001,065
September1424873
October44197620
November22145303
December41913151

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 0.9 km from Brenham. 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 USC00411048 (Brenham). Public domain.