Austin climate

Austin Frost Dates and Growing Season

NOAA 1991-2020 normals for Austin-Camp Mabry, 6.2 km from Austin, elevation 670 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Austin-Camp Mabry. 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 20 and the first fall freeze around December 3, a growing season of about 291 days.

Median at 36°F
last March 6, first November 22
Median at 32°F
last February 20, first December 3
Median at 28°F
last February 1, 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 27Mar 19Mar 15Mar 11Mar 6Mar 3Feb 27Feb 22Feb 14
32°FMar 14Mar 7Mar 2Feb 26Feb 20Feb 15Feb 9Feb 1Jan 23
28°FMar 3Feb 21Feb 13Feb 6Feb 1Jan 27Jan 20Jan 11Dec 29
24°FFeb 18Feb 8Feb 2Jan 27Jan 20Jan 15Jan 8Jan 2Dec 24
20°FFeb 11Feb 3Feb 1Jan 22Jan 19Jan 14Jan 8Jan 5Jan 4
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 5Nov 10Nov 15Nov 18Nov 22Nov 26Nov 29Dec 3Dec 10
32°FNov 15Nov 21Nov 26Nov 30Dec 3Dec 8Dec 13Dec 23Jan 1
28°FNov 27Dec 3Dec 10Dec 18Dec 27Jan 1Jan 6Jan 15Feb 1
24°FDec 12Dec 25Jan 1Jan 4Jan 7Jan 13Jan 20Feb 1Feb 10
20°FJan 2Jan 4Jan 6Jan 10Jan 15Jan 20Feb 1Feb 2Feb 8
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°F288279273267261255250243235
32°F326313305298291284277269258
28°F365353343335329321312303288
24°F365365365365365360349337325
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
99% of years
28°F or colder
88% of years
24°F or colder
46% of years
20°F or colder
10% 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
1,442
Cooling degree days, base 65°F
3,290
Growing degree days, base 40°F
11,002
Growing degree days, base 45°F
9,236
Growing degree days, base 50°F
7,547
Growing degree days, base 55°F
5,978
Growing degree days, base 60°F
4,553

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January40810151
February27224215
March14373408
April34172589
May3370832
June0541991
July06451,110
August06651,130
September1474923
October32238672
November18262350
December36816177

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 6.2 km from Austin. 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 USW00013958 (Austin-Camp Mabry). Public domain.