Calhoun County climate

Calhoun County Frost Dates and Growing Season

NOAA 1991-2020 normals for Aransas Wr, 23.6 km from Calhoun County, elevation 15 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Aransas Wr. 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 7 and the first fall freeze around December 13, a growing season of about 306 days.

Median at 36°F
last February 28, first December 1
Median at 32°F
last February 7, first December 13
Median at 28°F
last January 27, first December 29

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 24Mar 14Mar 8Mar 3Feb 28Feb 22Feb 15Feb 7Jan 28
32°FMar 11Mar 2Feb 24Feb 15Feb 7Jan 31Jan 26Jan 17Jan 2
28°FMar 2Feb 19Feb 9Feb 1Jan 27Jan 16Jan 9Dec 31Dec 18
24°FFeb 20Feb 9Feb 1Jan 25Jan 17Jan 9Jan 4Dec 30Dec 20
20°FFeb 9Jan 31Jan 20Jan 13Jan 8Jan 5Jan 1Dec 24Dec 15
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 17Nov 24Nov 28Dec 1Dec 4Dec 9Dec 14Dec 24
32°FNov 22Nov 30Dec 4Dec 8Dec 13Dec 19Dec 27Jan 2Jan 13
28°FDec 2Dec 8Dec 14Dec 20Dec 29Jan 2Jan 8Jan 19Feb 1
24°FDec 12Dec 20Dec 29Jan 2Jan 7Jan 13Jan 23Feb 1Feb 10
20°FDec 15Dec 23Dec 31Jan 4Jan 7Jan 9Jan 14Jan 28Feb 4
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°F311299292285279273265254243
32°F346334324314306300291280267
28°F365365357348340334323311297
24°F365365365365365365354343330
20°F365365365365365365365365358
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
97% of years
28°F or colder
76% of years
24°F or colder
39% of years
20°F or colder
13% of years
16°F or colder
2% 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
1,123
Cooling degree days, base 65°F
3,059
Growing degree days, base 40°F
11,075
Growing degree days, base 45°F
9,282
Growing degree days, base 50°F
7,545
Growing degree days, base 55°F
5,907
Growing degree days, base 60°F
4,401

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3506175
February22217243
March10762427
April24171597
May2361825
June0502952
July05571,022
August05701,035
September0438888
October17268716
November10987434
December29320232

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 23.6 km from Calhoun 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 USC00410305 (Aransas Wr). Public domain.