Lavaca County climate

Lavaca County Frost Dates and Growing Season

NOAA 1991-2020 normals for Hallettsville 2 N, 9.7 km from Lavaca County, elevation 275 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hallettsville 2 N. 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 February 17 and the first fall freeze around December 4, a growing season of about 297 days.

Median at 36°F
last March 5, first November 23
Median at 32°F
last February 17, first December 4
Median at 28°F
last January 30, first December 27

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 29Mar 21Mar 13Mar 9Mar 5Mar 1Feb 24Feb 19Feb 9
32°FMar 13Mar 5Feb 28Feb 23Feb 17Feb 10Feb 3Jan 28Jan 19
28°FFeb 28Feb 19Feb 12Feb 4Jan 30Jan 24Jan 17Jan 7Dec 24
24°FFeb 16Feb 5Jan 31Jan 22Jan 17Jan 9Jan 3Dec 28Dec 14
20°FFeb 3Jan 29Jan 17Jan 13Jan 8Jan 5Jan 1Dec 25Dec 17
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 4Nov 10Nov 14Nov 18Nov 23Nov 27Dec 1Dec 4Dec 12
32°FNov 14Nov 21Nov 26Dec 1Dec 4Dec 9Dec 17Dec 29Jan 8
28°FNov 28Dec 5Dec 10Dec 18Dec 27Jan 2Jan 10Jan 19Feb 3
24°FDec 7Dec 15Dec 24Jan 1Jan 4Jan 9Jan 17Jan 26Feb 6
20°FDec 14Dec 22Dec 31Jan 4Jan 6Jan 9Jan 15Jan 24Feb 1
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°F295283276269263257251243234
32°F332320310303297289280272262
28°F365357345337331324316306293
24°F365365365365365360352339326
20°F365365365365365365365365360
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
86% of years
24°F or colder
44% of years
20°F or colder
13% of years
16°F or colder
1% 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
1,112
Cooling degree days, base 65°F
3,587
Growing degree days, base 40°F
11,615
Growing degree days, base 45°F
9,824
Growing degree days, base 50°F
8,090
Growing degree days, base 55°F
6,452
Growing degree days, base 60°F
4,943

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January32725219
February21143278
March102109479
April22213641
May1417880
June05591,009
July06451,110
August06601,125
September0501951
October19287734
November13696421
December29533244

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 9.7 km from Lavaca County. 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 USC00413873 (Hallettsville 2 N). Public domain.