Darrington climate

Darrington Frost Dates and Growing Season

NOAA 1991-2020 normals for Darrington RS, 0.6 km from Darrington, elevation 550 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Darrington RS. 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 April 16 and the first fall freeze around October 23, a growing season of about 190 days.

Median at 36°F
last May 3, first October 8
Median at 32°F
last April 16, first October 23
Median at 28°F
last March 22, first November 7

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°FMay 20May 14May 10May 7May 3May 1Apr 28Apr 24Apr 17
32°FMay 5May 1Apr 26Apr 20Apr 16Apr 10Apr 6Apr 1Mar 27
28°FApr 10Apr 4Mar 31Mar 26Mar 22Mar 17Mar 13Mar 7Mar 1
24°FMar 19Mar 12Mar 5Mar 1Feb 26Feb 19Feb 11Feb 3Jan 16
20°FMar 3Feb 24Feb 17Feb 9Feb 1Jan 21Jan 11Jan 2Dec 20
16°FFeb 23Feb 15Feb 4Jan 26Jan 14Jan 5Dec 30Dec 19Dec 8

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°FSep 25Sep 30Oct 2Oct 5Oct 8Oct 11Oct 14Oct 18Oct 23
32°FOct 6Oct 13Oct 16Oct 19Oct 23Oct 25Oct 29Nov 2Nov 9
28°FOct 20Oct 25Oct 30Nov 3Nov 7Nov 11Nov 18Nov 23Nov 29
24°FNov 4Nov 11Nov 18Nov 23Nov 27Dec 1Dec 7Dec 14Dec 23
20°FNov 19Nov 27Dec 1Dec 8Dec 14Dec 20Dec 26Jan 1Jan 15
16°FNov 27Dec 3Dec 11Dec 17Dec 23Dec 29Jan 2Jan 13Feb 6

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°F178171166160156151147142134
32°F216207200194190184179172164
28°F263251243237232226219212203
24°F317302292283276270263255244
20°F359346334327319310302291277
16°F365365365357348337329318307

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
93% of years
16°F or colder
71% 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
5,809
Cooling degree days, base 65°F
219
Growing degree days, base 40°F
4,080
Growing degree days, base 45°F
2,873
Growing degree days, base 50°F
1,908
Growing degree days, base 55°F
1,141
Growing degree days, base 60°F
578

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January91900
February76301
March70509
April497153
May2988195
June16724308
July5979485
August4789507
September18219289
October498058
November74302
December93200

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 0.6 km from Darrington. 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 USC00451992 (Darrington RS). Public domain.