Presidio climate

Presidio Frost Dates and Growing Season

NOAA 1991-2020 normals for Presidio, 1.1 km from Presidio, elevation 2610 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Presidio. 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 23 and the first fall freeze around November 26, a growing season of about 275 days.

Median at 36°F
last March 7, first November 16
Median at 32°F
last February 23, first November 26
Median at 28°F
last February 3, first December 5

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 24Mar 17Mar 13Mar 10Mar 7Mar 5Mar 2Feb 26Feb 19
32°FMar 13Mar 7Mar 4Feb 28Feb 23Feb 18Feb 14Feb 8Feb 3
28°FFeb 27Feb 19Feb 12Feb 7Feb 3Jan 31Jan 29Jan 24Jan 17
24°FFeb 9Feb 1Jan 28Jan 25Jan 20Jan 14Jan 8Jan 2Dec 25
20°FJan 31Jan 22Jan 17Jan 11Jan 6Jan 2Dec 29Dec 24Dec 15
16°FFeb 1Jan 21Jan 16Jan 7Jan 3Jan 1Dec 28Dec 23Dec 18

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 1Nov 6Nov 10Nov 14Nov 16Nov 20Nov 23Nov 26Dec 1
32°FNov 9Nov 15Nov 19Nov 23Nov 26Nov 29Dec 1Dec 4Dec 9
28°FNov 19Nov 25Nov 30Dec 2Dec 5Dec 7Dec 10Dec 15Dec 21
24°FDec 1Dec 6Dec 9Dec 12Dec 17Dec 20Dec 25Dec 31Jan 8
20°FDec 8Dec 13Dec 19Dec 23Dec 27Jan 1Jan 4Jan 10Jan 19
16°FDec 14Dec 20Dec 25Dec 29Jan 2Jan 5Jan 12Jan 18Feb 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°F274267261257253249244238229
32°F300292286281275270265259251
28°F330321313308303298291284274
24°F360351345339334330323316306
20°F365365365365360355349343334
16°F365365365365365365365365355

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
93% of years
20°F or colder
58% of years
16°F or colder
21% 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
1,371
Cooling degree days, base 65°F
3,785
Growing degree days, base 40°F
11,556
Growing degree days, base 45°F
9,769
Growing degree days, base 50°F
8,053
Growing degree days, base 55°F
6,468
Growing degree days, base 60°F
5,046

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January439096
February2268219
March9073451
April12255693
May0517981
June07031,153
July07161,181
August07001,165
September1509959
October15264715
November16237335
December4271104

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 1.1 km from Presidio. 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 USC00417262 (Presidio). Public domain.