Skagit County climate

Skagit County Frost Dates and Growing Season

NOAA 1991-2020 normals for Concrete Ppl Fish Stn, 7.8 km from Skagit County, elevation 195 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Concrete Ppl Fish Stn. 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 28 and the first fall freeze around November 14, a growing season of about 229 days.

Median at 36°F
last April 25, first October 25
Median at 32°F
last March 28, first November 14
Median at 28°F
last February 25, first December 2

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 11May 6May 2Apr 29Apr 25Apr 21Apr 17Apr 12Apr 5
32°FApr 19Apr 10Apr 5Apr 1Mar 28Mar 23Mar 18Mar 13Mar 7
28°FMar 20Mar 11Mar 6Mar 1Feb 25Feb 20Feb 14Feb 4Jan 19
24°FFeb 28Feb 22Feb 13Feb 3Jan 27Jan 18Jan 9Dec 31Dec 13
20°FFeb 19Feb 2Jan 26Jan 18Jan 9Jan 1Dec 23Dec 10Dec 5
16°FJan 29Jan 20Jan 12Jan 6Jan 1Dec 24Dec 11Dec 6Dec 2

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 8Oct 15Oct 19Oct 22Oct 25Oct 29Nov 1Nov 6Nov 13
32°FOct 23Oct 31Nov 5Nov 9Nov 14Nov 19Nov 23Nov 27Dec 4
28°FNov 10Nov 16Nov 23Nov 27Dec 2Dec 6Dec 13Dec 21Jan 3
24°FNov 23Nov 30Dec 6Dec 11Dec 20Dec 29Jan 3Jan 14Feb 1
20°FNov 28Dec 5Dec 9Dec 18Dec 28Jan 2Jan 11Jan 23Feb 1
16°FNov 28Dec 4Dec 7Dec 14Dec 26Jan 1Jan 6Jan 14Jan 25

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°F212202196191187181175169162
32°F260251243236229224218211201
28°F324312302292285277269260247
24°F365361350342334327317306292
20°F365365365365365358344335323
16°F365365365365365365365365347

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
99% of years
24°F or colder
86% of years
20°F or colder
49% of years
16°F or colder
19% 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
5,325
Cooling degree days, base 65°F
137
Growing degree days, base 40°F
4,212
Growing degree days, base 45°F
2,888
Growing degree days, base 50°F
1,850
Growing degree days, base 55°F
1,042
Growing degree days, base 60°F
467

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January83500
February69301
March654010
April477053
May3054179
June18012283
July7046442
August5257470
September15417314
October414194
November65306
December83800

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 7.8 km from Skagit County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00451679 (Concrete Ppl Fish Stn). Public domain.