Selah climate

Selah Frost Dates and Growing Season

NOAA 1991-2020 normals for Selah 2 Ne, 3.1 km from Selah, elevation 1120 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Selah 2 Ne. 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 5 and the first fall freeze around October 4, a growing season of about 149 days.

Median at 36°F
last May 24, first September 24
Median at 32°F
last May 5, first October 4
Median at 28°F
last April 23, first October 17

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 12Jun 6Jun 1May 29May 24May 21May 17May 12May 6
32°FMay 23May 17May 13May 9May 5May 3Apr 30Apr 28Apr 24
28°FMay 7May 1Apr 29Apr 26Apr 23Apr 20Apr 16Apr 11Apr 7
24°FApr 26Apr 17Apr 12Apr 7Apr 2Mar 30Mar 26Mar 21Mar 12
20°FApr 3Mar 25Mar 19Mar 14Mar 9Mar 5Mar 1Feb 26Feb 19
16°FMar 9Mar 2Feb 28Feb 24Feb 20Feb 15Feb 8Feb 1Jan 18

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 10Sep 15Sep 19Sep 21Sep 24Sep 26Sep 28Oct 1Oct 5
32°FSep 23Sep 27Sep 29Oct 1Oct 4Oct 6Oct 10Oct 13Oct 18
28°FOct 2Oct 7Oct 11Oct 14Oct 17Oct 20Oct 23Oct 26Oct 31
24°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 4Nov 9Nov 17
20°FOct 25Oct 31Nov 4Nov 7Nov 11Nov 15Nov 20Nov 24Dec 1
16°FNov 2Nov 10Nov 15Nov 20Nov 24Nov 28Dec 2Dec 8Dec 16

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°F14313613012512011511010495
32°F168162157154149146142136128
28°F199191185181177173168162155
24°F238229222217211205201195184
20°F274263256250245239234227216
16°F315300293284277272265258248

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
100% of years
16°F or colder
100% 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
6,209
Cooling degree days, base 65°F
485
Growing degree days, base 40°F
4,446
Growing degree days, base 45°F
3,319
Growing degree days, base 50°F
2,371
Growing degree days, base 55°F
1,582
Growing degree days, base 60°F
950

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,10000
February85300
March73506
April503057
May25918242
June10760404
July18201648
August22169612
September15535334
October498066
November83702
December1,12200

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 3.1 km from Selah. 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 USC00457522 (Selah 2 Ne). Public domain.