Crockett County climate

Crockett County Frost Dates and Growing Season

NOAA 1991-2020 normals for Ozona, 19.7 km from Crockett County, elevation 2345 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ozona. 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 March 21 and the first fall freeze around November 6, a growing season of about 227 days.

Median at 36°F
last April 7, first October 31
Median at 32°F
last March 21, first November 6
Median at 28°F
last March 8, first November 16

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°FApr 25Apr 19Apr 14Apr 10Apr 7Apr 4Apr 1Mar 27Mar 18
32°FApr 12Apr 5Mar 31Mar 26Mar 21Mar 17Mar 13Mar 8Mar 3
28°FMar 29Mar 20Mar 16Mar 12Mar 8Mar 5Mar 2Feb 26Feb 20
24°FMar 15Mar 9Mar 4Mar 1Feb 26Feb 22Feb 17Feb 11Feb 3
20°FMar 6Mar 1Feb 21Feb 13Feb 7Feb 2Jan 29Jan 20Jan 7
16°FFeb 25Feb 11Feb 3Jan 29Jan 19Jan 10Dec 31Dec 22Dec 9

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°FOct 17Oct 21Oct 24Oct 28Oct 31Nov 1Nov 4Nov 6Nov 11
32°FOct 24Oct 29Nov 1Nov 4Nov 6Nov 8Nov 12Nov 16Nov 21
28°FNov 1Nov 5Nov 9Nov 12Nov 16Nov 19Nov 23Nov 27Dec 2
24°FNov 10Nov 15Nov 19Nov 23Nov 27Nov 30Dec 4Dec 9Dec 17
20°FNov 19Nov 27Dec 1Dec 4Dec 10Dec 16Dec 24Dec 31Jan 10
16°FNov 30Dec 5Dec 12Dec 20Dec 26Jan 1Jan 7Jan 20Feb 4

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°F226218212208204199195190181
32°F250243237232227222217210202
28°F275266260256251247242237228
24°F306295288282275270264258250
20°F344333325317309301293284271
16°F365365365358347339333320305

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
100% of years
24°F or colder
100% of years
20°F or colder
98% of years
16°F or colder
72% 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
2,485
Cooling degree days, base 65°F
2,367
Growing degree days, base 40°F
9,104
Growing degree days, base 45°F
7,443
Growing degree days, base 50°F
5,933
Growing degree days, base 55°F
4,590
Growing degree days, base 60°F
3,402

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January622036
February443182
March26915246
April8995462
May12290743
June0474924
July05381,003
August0519984
September5327773
October94102480
November3587159
December594043

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 19.7 km from Crockett 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 USC00416734 (Ozona). Public domain.