Dallas County climate

Dallas County Frost Dates and Growing Season

NOAA 1991-2020 normals for Selma, 12.8 km from Dallas County, elevation 147 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Selma. 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 8 and the first fall freeze around November 18, a growing season of about 254 days.

Median at 36°F
last March 25, first November 7
Median at 32°F
last March 8, first November 18
Median at 28°F
last February 24, first December 1

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 13Apr 5Apr 1Mar 29Mar 25Mar 21Mar 15Mar 10Mar 2
32°FMar 28Mar 22Mar 17Mar 13Mar 8Mar 3Feb 28Feb 24Feb 15
28°FMar 16Mar 9Mar 2Feb 28Feb 24Feb 17Feb 12Feb 4Jan 28
24°FMar 3Feb 26Feb 17Feb 9Feb 3Jan 31Jan 26Jan 17Jan 4
20°FFeb 21Feb 8Feb 1Jan 30Jan 25Jan 19Jan 12Jan 6Dec 29
16°FFeb 4Jan 31Jan 29Jan 23Jan 18Jan 12Jan 8Jan 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 26Oct 30Nov 1Nov 4Nov 7Nov 9Nov 13Nov 17Nov 23
32°FNov 2Nov 6Nov 11Nov 15Nov 18Nov 22Nov 27Dec 1Dec 8
28°FNov 12Nov 18Nov 24Nov 28Dec 1Dec 6Dec 12Dec 24Jan 1
24°FNov 26Dec 3Dec 10Dec 19Dec 25Jan 1Jan 5Jan 11Jan 24
20°FDec 8Dec 22Dec 30Jan 1Jan 5Jan 10Jan 15Jan 23Feb 2
16°FDec 25Jan 1Jan 5Jan 8Jan 12Jan 17Jan 22Jan 28Feb 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°F254245238233227223218212204
32°F284272265259254250245238230
28°F319307298290284278270263253
24°F354341334326318312305297283
20°F365365365358349341334326312
16°F365365365365365365365353338

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
94% of years
20°F or colder
66% of years
16°F or colder
30% 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
2,113
Cooling degree days, base 65°F
2,468
Growing degree days, base 40°F
9,548
Growing degree days, base 45°F
7,846
Growing degree days, base 50°F
6,268
Growing degree days, base 55°F
4,840
Growing degree days, base 60°F
3,568

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January544386
February3897123
March23932284
April8587454
May12264716
June0450900
July05421,007
August05351,000
September2381829
October68141540
November28822220
December4865109

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 12.8 km from Dallas County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00017366 (Selma). Public domain.