Willows climate

Willows Frost Dates and Growing Season

NOAA 1991-2020 normals for Willows 6 W, 9.5 km from Willows, elevation 234 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Willows 6 W. 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 21 and the first fall freeze around December 6, a growing season of about 289 days.

Median at 36°F
last April 2, first November 23
Median at 32°F
last February 21, first December 6
Median at 28°F
last January 5, first December 18

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°FApr 25Apr 17Apr 12Apr 7Apr 2Mar 27Mar 20Mar 10Feb 25
32°FApr 9Mar 29Mar 13Mar 1Feb 21Feb 11Jan 30Jan 15Jan 4
28°FFeb 24Feb 5Jan 24Jan 14Jan 5Dec 31Dec 28Dec 21Dec 14
24°FJan 20Jan 11Jan 4Dec 31Dec 29Dec 23Dec 19Dec 14Dec 9
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 7Nov 12Nov 15Nov 20Nov 23Nov 26Nov 29Dec 2Dec 7
32°FNov 16Nov 24Nov 29Dec 2Dec 6Dec 10Dec 14Dec 18Dec 29
28°FNov 30Dec 5Dec 11Dec 15Dec 18Dec 24Dec 30Jan 6Jan 27
24°FDec 8Dec 13Dec 17Dec 20Dec 25Dec 29Jan 1Jan 7Jan 18
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°F275258248239233227221215205
32°F334321308300289278266254235
28°F365365365356348341334323303
24°F365365365365365365365365355
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
18% of years
20°F or colder
1% 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
2,185
Cooling degree days, base 65°F
1,732
Growing degree days, base 40°F
8,677
Growing degree days, base 45°F
6,893
Growing degree days, base 50°F
5,247
Growing degree days, base 55°F
3,840
Growing degree days, base 60°F
2,683

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January490051
February355099
March2845201
April15535333
May47148566
June7311754
July0429894
August0386851
September3294741
October53118530
November2875184
December505043

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 9.5 km from Willows. 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 USC00049699 (Willows 6 W). Public domain.