White Salmon climate

White Salmon Frost Dates and Growing Season

NOAA 1991-2020 normals for Hood Rvr Exp Stn, 5.4 km from White Salmon, elevation 500 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hood Rvr Exp 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 April 20 and the first fall freeze around October 13, a growing season of about 177 days.

Median at 36°F
last May 7, first October 1
Median at 32°F
last April 20, first October 13
Median at 28°F
last March 20, first October 28

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 25May 18May 14May 10May 7May 3Apr 30Apr 28Apr 23
32°FMay 9May 2Apr 28Apr 25Apr 20Apr 16Apr 11Apr 5Mar 29
28°FApr 10Apr 3Mar 29Mar 25Mar 20Mar 16Mar 12Mar 6Feb 28
24°FMar 14Mar 7Mar 3Feb 28Feb 24Feb 19Feb 14Feb 5Jan 16
20°FMar 5Feb 25Feb 18Feb 11Feb 3Jan 23Jan 12Jan 3Dec 18
16°FFeb 25Feb 15Feb 5Jan 28Jan 17Jan 9Jan 3Dec 24Dec 7

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 15Sep 21Sep 25Sep 28Oct 1Oct 3Oct 5Oct 9Oct 16
32°FSep 30Oct 3Oct 6Oct 9Oct 13Oct 16Oct 20Oct 25Nov 1
28°FOct 8Oct 14Oct 20Oct 23Oct 28Nov 1Nov 4Nov 10Nov 21
24°FOct 25Oct 31Nov 5Nov 10Nov 17Nov 24Nov 30Dec 6Dec 21
20°FNov 6Nov 18Nov 26Dec 1Dec 7Dec 16Dec 26Jan 2Jan 26
16°FNov 20Dec 1Dec 6Dec 14Dec 26Jan 1Jan 8Jan 22Feb 9

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°F167159154150146140136130121
32°F206196190184177172167161152
28°F254243236229223217211203194
24°F314299289280271262254245236
20°F359343331320310303293282266
16°F365365363353342333324311299

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
92% 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
5,412
Cooling degree days, base 65°F
380
Growing degree days, base 40°F
4,582
Growing degree days, base 45°F
3,314
Growing degree days, base 50°F
2,282
Growing degree days, base 55°F
1,455
Growing degree days, base 60°F
818

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January91100
February73601
March654012
April462165
May26315231
June12646371
July32144577
August30140575
September13634350
October436193
November70708
December91801

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 5.4 km from White Salmon. 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 USC00354003 (Hood Rvr Exp Stn). Public domain.