Skamania County climate

Skamania County Frost Dates and Growing Season

NOAA 1991-2020 normals for Carson Fish Hatchery, 17.8 km from Skamania County, elevation 1134 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Carson Fish Hatchery. 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 May 2 and the first fall freeze around October 9, a growing season of about 161 days.

Median at 36°F
last May 21, first September 24
Median at 32°F
last May 2, first October 9
Median at 28°F
last April 7, first October 30

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°FJun 10Jun 3May 30May 25May 21May 18May 15May 11May 6
32°FMay 20May 13May 9May 5May 2Apr 30Apr 27Apr 23Apr 15
28°FMay 1Apr 25Apr 18Apr 12Apr 7Mar 31Mar 27Mar 21Mar 12
24°FMar 24Mar 15Mar 9Mar 3Mar 1Feb 25Feb 19Feb 11Jan 24
20°FMar 7Feb 28Feb 24Feb 17Feb 9Feb 1Jan 18Jan 7Dec 26
16°FMar 1Feb 23Feb 15Feb 6Jan 29Jan 16Jan 6Dec 29Dec 10

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

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°F14714013412912411911410798
32°F188178171165161156151145136
28°F243230222216208202193185174
24°F306293284274268261254245234
20°F354338329319311303296286270
16°F365365362349337328317308296

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
94% of years
16°F or colder
75% 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
6,291
Cooling degree days, base 65°F
207
Growing degree days, base 40°F
3,745
Growing degree days, base 45°F
2,628
Growing degree days, base 50°F
1,725
Growing degree days, base 55°F
1,021
Growing degree days, base 60°F
518

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January98000
February81200
March76103
April572031
May3584151
June21020264
July7884471
August7182476
September20017272
October505054
November76203
December98300

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 17.8 km from Skamania County. 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 USC00451160 (Carson Fish Hatchery). Public domain.