Vail climate

Vail Frost Dates and Growing Season

NOAA 1991-2020 normals for Tucson Intl AP, 24.7 km from Vail, elevation 2549 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tucson Intl 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 5 and the first fall freeze around December 9, a growing season of about 307 days.

Median at 36°F
last February 28, first November 26
Median at 32°F
last February 5, first December 9
Median at 28°F
last January 11, first December 26

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 12Mar 7Mar 3Feb 28Feb 25Feb 19Feb 13Feb 3
32°FMar 2Feb 23Feb 17Feb 11Feb 5Jan 31Jan 23Jan 14Jan 4
28°FFeb 17Feb 6Jan 31Jan 19Jan 11Jan 5Jan 1Dec 24Dec 14
24°FFeb 7Jan 29Jan 20Jan 12Jan 5Jan 2Dec 30Dec 22Dec 12
20°F–––––––––
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 11Nov 17Nov 20Nov 23Nov 26Nov 30Dec 3Dec 8Dec 14
32°FNov 21Nov 26Nov 30Dec 5Dec 9Dec 13Dec 17Dec 24Jan 3
28°FNov 30Dec 9Dec 14Dec 20Dec 26Jan 1Jan 6Jan 18Feb 1
24°FDec 10Dec 18Dec 25Jan 1Jan 3Jan 7Jan 14Jan 27Feb 4
20°F–––––––––
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°F301289283276271265258251241
32°F344333323315307300293284274
28°F365365365358351343335326314
24°F365365365365365365365365348
20°F365365365365365365365365365
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
99% of years
28°F or colder
70% of years
24°F or colder
19% of years
20°F or colder
3% of years
16°F or colder
0% 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
1,333
Cooling degree days, base 65°F
3,424
Growing degree days, base 40°F
11,220
Growing degree days, base 45°F
9,415
Growing degree days, base 50°F
7,673
Growing degree days, base 55°F
6,062
Growing degree days, base 60°F
4,639

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3531147
February2515192
March13842373
April44137544
May4370831
June06341,084
July07211,186
August06791,144
September0532982
October18256702
November15146352
December3731136

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 24.7 km from Vail. 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 USW00023160 (Tucson Intl AP). Public domain.