Dallas County climate

Dallas County Frost Dates and Growing Season

NOAA 1991-2020 normals for Sparkman, 17.1 km from Dallas County, elevation 170 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sparkman. 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 29 and the first fall freeze around November 4, a growing season of about 223 days.

Median at 36°F
last April 9, first October 26
Median at 32°F
last March 29, first November 4
Median at 28°F
last March 10, first November 17

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 29Apr 23Apr 18Apr 13Apr 9Apr 6Apr 2Mar 30Mar 22
32°FApr 18Apr 9Apr 4Apr 1Mar 29Mar 24Mar 20Mar 13Mar 5
28°FApr 4Mar 27Mar 20Mar 15Mar 10Mar 6Mar 2Feb 27Feb 18
24°FMar 15Mar 8Mar 4Mar 1Feb 25Feb 21Feb 15Feb 7Jan 29
20°FMar 4Feb 26Feb 18Feb 11Feb 4Jan 31Jan 26Jan 17Jan 6
16°FFeb 23Feb 9Feb 2Jan 30Jan 24Jan 18Jan 11Jan 5Dec 30

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 12Oct 16Oct 19Oct 23Oct 26Oct 29Nov 1Nov 3Nov 8
32°FOct 21Oct 26Oct 30Nov 1Nov 4Nov 7Nov 11Nov 16Nov 24
28°FOct 31Nov 4Nov 9Nov 13Nov 17Nov 22Nov 26Dec 2Dec 9
24°FNov 10Nov 17Nov 23Nov 27Dec 1Dec 7Dec 14Dec 23Jan 1
20°FNov 24Dec 1Dec 8Dec 17Dec 25Dec 30Jan 3Jan 9Jan 19
16°FDec 8Dec 21Dec 29Jan 1Jan 5Jan 9Jan 15Jan 21Feb 1

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°F223215209203198194189183176
32°F249240234227223218212205196
28°F279270262255249244238230220
24°F316304296288282275269260250
20°F356340332323314307301291277
16°F365365365358349340334325310

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
96% of years
16°F or colder
69% 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
3,065
Cooling degree days, base 65°F
1,958
Growing degree days, base 40°F
8,226
Growing degree days, base 45°F
6,659
Growing degree days, base 50°F
5,247
Growing degree days, base 55°F
3,992
Growing degree days, base 60°F
2,894

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January733133
February546252
March37112173
April15047356
May35186617
June1378826
July0504969
August0476941
September12280718
October16263377
November4078135
December648250

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 17.1 km from Dallas 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 USC00036768 (Sparkman). Public domain.