Sundown climate

Sundown Frost Dates and Growing Season

NOAA 1991-2020 normals for Levelland, 14.8 km from Sundown, elevation 3514 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Levelland. 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 9 and the first fall freeze around November 1, a growing season of about 205 days.

Median at 36°F
last April 19, first October 22
Median at 32°F
last April 9, first November 1
Median at 28°F
last March 28, first November 9

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 1Apr 28Apr 25Apr 22Apr 19Apr 17Apr 13Apr 10Apr 4
32°FApr 25Apr 20Apr 15Apr 12Apr 9Apr 5Apr 2Mar 29Mar 23
28°FApr 15Apr 8Apr 3Mar 31Mar 28Mar 23Mar 18Mar 13Mar 8
24°FApr 2Mar 27Mar 21Mar 15Mar 12Mar 8Mar 5Mar 1Feb 24
20°FMar 18Mar 11Mar 7Mar 3Feb 28Feb 24Feb 19Feb 14Feb 6
16°FMar 7Mar 1Feb 24Feb 17Feb 10Feb 5Jan 31Jan 20Jan 6

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 8Oct 14Oct 17Oct 20Oct 22Oct 24Oct 27Oct 31Nov 3
32°FOct 18Oct 23Oct 27Oct 30Nov 1Nov 3Nov 5Nov 8Nov 13
28°FOct 26Nov 1Nov 4Nov 6Nov 9Nov 12Nov 14Nov 18Nov 23
24°FNov 3Nov 8Nov 12Nov 15Nov 18Nov 22Nov 25Nov 30Dec 4
20°FNov 10Nov 17Nov 23Nov 26Nov 30Dec 4Dec 8Dec 14Dec 21
16°FNov 23Nov 29Dec 4Dec 10Dec 15Dec 20Dec 26Jan 1Jan 14

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°F203196192188184180177172166
32°F224217212208205201197191184
28°F248241234230226221216211203
24°F274266260255249245238232225
20°F303293286280275268263257248
16°F340330320312305300293285273

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
98% 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
3,597
Cooling degree days, base 65°F
1,598
Growing degree days, base 40°F
7,479
Growing degree days, base 45°F
5,978
Growing degree days, base 50°F
4,638
Growing degree days, base 55°F
3,464
Growing degree days, base 60°F
2,454

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January792012
February607034
March4453125
April20926291
May56166577
June2363811
July0434899
August1382846
September28185609
October19338332
November507186
December759016

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 14.8 km from Sundown. 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 USC00415183 (Levelland). Public domain.