La Porte climate

La Porte Frost Dates and Growing Season

NOAA 1991-2020 normals for Houston Nwso, 22.5 km from La Porte, elevation 19 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Houston Nwso. 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 January 31 and the first fall freeze around December 14, a growing season of about 317 days.

Median at 36°F
last February 22, first November 29
Median at 32°F
last January 31, first December 14
Median at 28°F
last January 17, first January 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°FMar 17Mar 9Mar 3Feb 27Feb 22Feb 16Feb 6Jan 31Jan 21
32°FMar 5Feb 24Feb 15Feb 5Jan 31Jan 25Jan 18Jan 7Dec 25
28°FFeb 24Feb 9Jan 31Jan 25Jan 17Jan 11Jan 5Dec 29Dec 19
24°FFeb 10Jan 29Jan 24Jan 17Jan 12Jan 8Jan 4Jan 1Dec 22
20°F–––––––––
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 9Nov 16Nov 20Nov 25Nov 29Dec 2Dec 6Dec 12Dec 22
32°FNov 19Nov 29Dec 3Dec 9Dec 14Dec 22Jan 1Jan 7Jan 19
28°FDec 6Dec 14Dec 22Dec 30Jan 3Jan 7Jan 14Jan 22Feb 5
24°FDec 20Dec 31Jan 2Jan 6Jan 9Jan 13Jan 20Jan 26Feb 3
20°F–––––––––
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°F315304296288281274267260249
32°F357344335327317309303294279
28°F365365365365356349340332317
24°F365365365365365365365363351
20°F365365365365365365365365365
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
94% of years
28°F or colder
60% of years
24°F or colder
21% of years
20°F or colder
3% of years
16°F or colder
0% 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
1,147
Cooling degree days, base 65°F
3,198
Growing degree days, base 40°F
11,186
Growing degree days, base 45°F
9,393
Growing degree days, base 50°F
7,660
Growing degree days, base 55°F
6,028
Growing degree days, base 60°F
4,534

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January33720202
February21334263
March10987449
April28174596
May1375839
June0520970
July05861,051
August05921,057
September0453903
October22244687
November14281399
December29434244

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 22.5 km from La Porte. 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 USC00414333 (Houston Nwso). Public domain.