Elmendorf climate

Elmendorf Frost Dates and Growing Season

NOAA 1991-2020 normals for San Antonio Stinson AP, 16.3 km from Elmendorf, elevation 571 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for San Antonio Stinson AP. 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 February 20 and the first fall freeze around December 3, a growing season of about 291 days.

Median at 36°F
last March 5, first November 21
Median at 32°F
last February 20, first December 3
Median at 28°F
last January 30, first December 23

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°FMar 27Mar 19Mar 13Mar 9Mar 5Mar 1Feb 25Feb 18Feb 8
32°FMar 13Mar 7Mar 2Feb 26Feb 20Feb 14Feb 5Jan 30Jan 20
28°FMar 5Feb 24Feb 14Feb 4Jan 30Jan 23Jan 17Jan 6Dec 25
24°FFeb 20Feb 5Jan 29Jan 22Jan 14Jan 8Jan 4Dec 30Dec 20
20°FFeb 14Jan 29Jan 19Jan 10Jan 7Jan 5Jan 3Jan 1Dec 29
16°F–––––––––

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°FNov 2Nov 8Nov 13Nov 17Nov 21Nov 25Nov 30Dec 3Dec 9
32°FNov 12Nov 20Nov 25Nov 29Dec 3Dec 7Dec 13Dec 20Jan 1
28°FNov 24Dec 1Dec 9Dec 16Dec 23Dec 30Jan 2Jan 8Jan 24
24°FDec 9Dec 20Dec 27Jan 1Jan 5Jan 8Jan 12Jan 22Feb 5
20°FDec 21Jan 1Jan 2Jan 4Jan 6Jan 8Jan 10Jan 20Feb 9
16°F–––––––––

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°F290279273267261255250243235
32°F325313305299291284276269258
28°F365353345336330321312302287
24°F365365365365365358349339325
20°F365365365365365365365365360
16°F365365365365365365365365365

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
90% of years
24°F or colder
50% of years
20°F or colder
12% of years
16°F or colder
1% 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
1,241
Cooling degree days, base 65°F
3,474
Growing degree days, base 40°F
11,371
Growing degree days, base 45°F
9,583
Growing degree days, base 50°F
7,858
Growing degree days, base 55°F
6,248
Growing degree days, base 60°F
4,779

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January36711168
February23135253
March11295454
April24207634
May1409873
June05641,014
July06431,108
August06681,133
September0488938
October24264706
November15571378
December32620200

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 16.3 km from Elmendorf. 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 USW00012970 (San Antonio Stinson AP). Public domain.