Driscoll Frost Dates and Growing Season

NOAA 1991-2020 normals for Robstown, 15.3 km from Driscoll, elevation 85 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Robstown. 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 26 and the first fall freeze around December 24, a growing season of about 336 days.

Median at 36°F: last February 15, first December 8
Median at 32°F: last January 26, first December 24
Median at 28°F: last January 10, first January 2

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	Mar 12	Mar 4	Feb 28	Feb 21	Feb 15	Feb 9	Feb 3	Jan 26	Jan 13
32°F	Mar 3	Feb 20	Feb 9	Feb 2	Jan 26	Jan 16	Jan 7	Dec 29	Dec 18
28°F	Feb 15	Feb 4	Jan 30	Jan 20	Jan 10	Jan 3	Dec 30	Dec 21	Dec 10
24°F	–	–	–	–	–	–	–	–	–
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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	Nov 16	Nov 24	Nov 29	Dec 3	Dec 8	Dec 13	Dec 20	Dec 29	Jan 7
32°F	Nov 28	Dec 5	Dec 11	Dec 18	Dec 24	Jan 1	Jan 6	Jan 15	Feb 2
28°F	Dec 7	Dec 14	Dec 20	Dec 29	Jan 2	Jan 8	Jan 18	Jan 30	Feb 6
24°F	–	–	–	–	–	–	–	–	–
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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	337	324	314	305	297	289	280	273	262
32°F	365	365	354	344	336	329	319	305	290
28°F	365	365	365	365	365	365	360	348	333
24°F	365	365	365	365	365	365	365	365	365
20°F	365	365	365	365	365	365	365	365	365
16°F	365	365	365	365	365	365	365	365	365

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder: 99% of years
32°F or colder: 82% of years
28°F or colder: 36% of years
24°F or colder: 6% of years
20°F or colder: 0% 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: 821
Cooling degree days, base 65°F: 3,787
Growing degree days, base 40°F: 12,098
Growing degree days, base 45°F: 10,293
Growing degree days, base 50°F: 8,522
Growing degree days, base 55°F: 6,823
Growing degree days, base 60°F: 5,235

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	269	27	259
February	152	51	332
March	66	136	538
April	13	263	701
May	0	441	905
June	0	568	1,018
July	0	628	1,093
August	0	656	1,121
September	0	515	965
October	12	328	782
November	86	127	495
December	224	49	314

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 15.3 km from Driscoll. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00417677 (Robstown). Public domain.