Wasco County climate

Wasco County Frost Dates and Growing Season

NOAA 1991-2020 normals for Dufur, 32.8 km from Wasco County, elevation 1330 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dufur. 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 12 and the first fall freeze around October 7, a growing season of about 148 days.

Median at 36°F
last June 5, first September 22
Median at 32°F
last May 12, first October 7
Median at 28°F
last April 24, first October 24

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 23Jun 17Jun 13Jun 8Jun 5Jun 1May 29May 22May 14
32°FMay 31May 26May 20May 16May 12May 8May 4Apr 30Apr 25
28°FMay 10May 5May 1Apr 28Apr 24Apr 18Apr 13Apr 7Mar 30
24°FApr 18Apr 8Apr 2Mar 30Mar 26Mar 20Mar 14Mar 7Feb 28
20°FMar 22Mar 9Mar 1Feb 26Feb 20Feb 14Feb 7Jan 27Jan 12
16°FMar 1Feb 21Feb 13Feb 4Jan 30Jan 18Jan 11Jan 3Dec 22

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

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°F135126120116111105999385
32°F173164158153148143138133125
28°F213204197191185180173168160
24°F262249241234228222213206198
20°F316304292284277269260252239
16°F354339328321313304296284272

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
95% 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
5,660
Cooling degree days, base 65°F
413
Growing degree days, base 40°F
4,561
Growing degree days, base 45°F
3,324
Growing degree days, base 50°F
2,309
Growing degree days, base 55°F
1,489
Growing degree days, base 60°F
857

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January96600
February76701
March662010
April474160
May27313217
June12738362
July25166606
August27153591
September13041363
October446192
November76906
December99300

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 32.8 km from Wasco 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 USC00352440 (Dufur). Public domain.