Wilbur climate

Wilbur Frost Dates and Growing Season

NOAA 1991-2020 normals for Wilbur, 1.7 km from Wilbur, elevation 2262 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wilbur. 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 June 1 and the first fall freeze around September 22, a growing season of about 112 days.

Median at 32°F
last June 1, first September 22
Median at 28°F
last May 8, first October 3

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°F–––––––––
32°FJun 22Jun 14Jun 9Jun 5Jun 1May 28May 21May 16May 10
28°FJun 1May 23May 16May 11May 8May 5May 2Apr 29Apr 24
24°FMay 7May 3Apr 29Apr 26Apr 22Apr 19Apr 15Apr 9Mar 30
20°FApr 24Apr 16Apr 8Apr 2Mar 27Mar 18Mar 11Mar 6Feb 28
16°FMar 26Mar 13Mar 8Mar 4Mar 1Feb 26Feb 21Feb 16Feb 5

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°F–––––––––
32°FSep 2Sep 7Sep 12Sep 18Sep 22Sep 25Sep 29Oct 1Oct 5
28°FSep 18Sep 25Sep 29Oct 1Oct 3Oct 6Oct 9Oct 14Oct 20
24°FSep 30Oct 4Oct 8Oct 12Oct 16Oct 20Oct 24Oct 29Nov 5
20°FOct 8Oct 15Oct 20Oct 25Oct 29Nov 2Nov 7Nov 13Nov 20
16°FOct 21Oct 29Nov 3Nov 8Nov 13Nov 18Nov 22Nov 27Dec 4

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°F1019184777267615444
32°F139130124117112106999180
28°F171163157153148143137131120
24°F206195188182177171167161154
20°F249238230222215208200192182
16°F284274266259254248241232221

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
7,346
Cooling degree days, base 65°F
293
Growing degree days, base 40°F
3,627
Growing degree days, base 45°F
2,637
Growing degree days, base 50°F
1,813
Growing degree days, base 55°F
1,142
Growing degree days, base 60°F
633

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22000
February98600
March85301
April626022
May3666149
June19825282
July53129541
August60111516
September22822261
October611040
November93301
December1,21500

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 1.7 km from Wilbur. 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 USC00459238 (Wilbur). Public domain.