Clinton climate

Clinton Frost Dates and Growing Season

NOAA 1991-2020 normals for Everett Snohomish AP, 9.6 km from Clinton, elevation 606 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Everett Snohomish 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 March 9 and the first fall freeze around November 17, a growing season of about 250 days.

Median at 36°F
last April 3, first November 2
Median at 32°F
last March 9, first November 17
Median at 28°F
last February 13, first December 6

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

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°FOct 19Oct 24Oct 28Oct 30Nov 2Nov 6Nov 10Nov 14Nov 20
32°FOct 31Nov 6Nov 10Nov 13Nov 17Nov 21Nov 25Dec 1Dec 7
28°FNov 15Nov 22Nov 26Dec 1Dec 6Dec 11Dec 18Dec 28Jan 8
24°FNov 23Nov 30Dec 6Dec 12Dec 19Dec 29Jan 5Jan 19Feb 5
20°FNov 26Dec 2Dec 6Dec 12Dec 21Dec 31Jan 12Jan 25Feb 2
16°FNov 24Dec 1Dec 5Dec 8Dec 12Dec 18Dec 24Jan 1Jan 27

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°F236228221217211206201195185
32°F285272264257250245239233224
28°F340326317308300291284273262
24°F365365360350340333326315301
20°F365365365365365365360342332
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
98% of years
24°F or colder
74% of years
20°F or colder
34% of years
16°F or colder
12% 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
5,039
Cooling degree days, base 65°F
97
Growing degree days, base 40°F
4,362
Growing degree days, base 45°F
2,902
Growing degree days, base 50°F
1,771
Growing degree days, base 55°F
937
Growing degree days, base 60°F
373

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January73804
February63303
March611015
April470147
May3113167
June19310268
July8134419
August6338440
September16111300
October408093
November606014
December76602

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 9.6 km from Clinton. 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 USW00024222 (Everett Snohomish AP). Public domain.