Deaf Smith County climate

Deaf Smith County Frost Dates and Growing Season

NOAA 1991-2020 normals for Hereford, 24.9 km from Deaf Smith County, elevation 3820 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hereford. 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 April 17 and the first fall freeze around October 25, a growing season of about 189 days.

Median at 36°F
last April 27, first October 17
Median at 32°F
last April 17, first October 25
Median at 28°F
last April 5, first November 4

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°FMay 8May 4May 2Apr 30Apr 27Apr 25Apr 22Apr 19Apr 14
32°FMay 1Apr 26Apr 23Apr 19Apr 17Apr 14Apr 11Apr 7Apr 3
28°FApr 22Apr 16Apr 12Apr 8Apr 5Apr 3Mar 31Mar 25Mar 17
24°FApr 11Apr 6Apr 2Mar 30Mar 24Mar 20Mar 14Mar 10Mar 5
20°FMar 31Mar 22Mar 16Mar 12Mar 8Mar 4Mar 1Feb 25Feb 18
16°FMar 13Mar 6Mar 2Feb 27Feb 23Feb 18Feb 14Feb 8Jan 31

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 2Oct 7Oct 11Oct 14Oct 17Oct 19Oct 21Oct 24Oct 28
32°FOct 11Oct 17Oct 20Oct 23Oct 25Oct 28Oct 31Nov 2Nov 6
28°FOct 22Oct 27Oct 31Nov 1Nov 4Nov 6Nov 9Nov 13Nov 17
24°FNov 1Nov 5Nov 8Nov 11Nov 13Nov 16Nov 19Nov 23Nov 28
20°FNov 7Nov 13Nov 17Nov 20Nov 23Nov 26Nov 29Dec 2Dec 8
16°FNov 16Nov 22Nov 27Dec 1Dec 4Dec 8Dec 12Dec 17Dec 24

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°F187182177174170167163159153
32°F208202197193189185181177172
28°F233226220215211206203197190
24°F257250245239235229224217210
20°F284276269264259254249242232
16°F314304297291285281274267258

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
100% of years
16°F or colder
100% 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
4,175
Cooling degree days, base 65°F
1,449
Growing degree days, base 40°F
6,940
Growing degree days, base 45°F
5,522
Growing degree days, base 50°F
4,264
Growing degree days, base 55°F
3,174
Growing degree days, base 60°F
2,240

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January87406
February689019
March518291
April28314227
May92114491
June4316762
July1422887
August1376840
September38178591
October24526282
November577161
December85408

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 24.9 km from Deaf Smith 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 USC00414098 (Hereford). Public domain.