Smith Corner climate

Smith Corner Frost Dates and Growing Season

NOAA 1991-2020 normals for Wasco, 14 km from Smith Corner, elevation 291 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wasco. 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 January 31 and the first fall freeze around December 5, a growing season of about 315 days.

Median at 36°F
last February 26, first November 24
Median at 32°F
last January 31, first December 5
Median at 28°F
last January 4, first December 16

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°FMar 25Mar 14Mar 7Mar 1Feb 26Feb 22Feb 15Feb 8Jan 30
32°FFeb 27Feb 16Feb 11Feb 5Jan 31Jan 25Jan 18Jan 10Jan 2
28°FFeb 4Jan 27Jan 17Jan 10Jan 4Dec 31Dec 28Dec 19Dec 8
24°FJan 17Jan 10Jan 2Dec 31Dec 29Dec 23Dec 20Dec 14Dec 8
20°F–––––––––
16°F–––––––––

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°FNov 9Nov 15Nov 18Nov 21Nov 24Nov 27Nov 30Dec 4Dec 10
32°FNov 21Nov 26Nov 29Dec 1Dec 5Dec 9Dec 13Dec 22Jan 2
28°FNov 29Dec 3Dec 8Dec 12Dec 16Dec 23Dec 29Jan 3Jan 16
24°FDec 4Dec 9Dec 13Dec 18Dec 23Dec 28Dec 29Jan 1Jan 14
20°F–––––––––
16°F–––––––––

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°F302290283276271264259251241
32°F344334327320315308300292278
28°F365365365361352345339333324
24°F365365365365365365365365355
20°F365365365365365365365365365
16°F365365365365365365365365365

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
97% of years
28°F or colder
65% of years
24°F or colder
17% of years
20°F or colder
0% of years
16°F or colder
0% 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
1,995
Cooling degree days, base 65°F
2,378
Growing degree days, base 40°F
9,514
Growing degree days, base 45°F
7,742
Growing degree days, base 50°F
6,093
Growing degree days, base 55°F
4,638
Growing degree days, base 60°F
3,403

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January501054
February3211122
March20511276
April10465412
May21227671
June2410858
July06011,066
August05461,011
September1381829
October46131550
November2736200
December522043

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 14 km from Smith Corner. 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 USC00049452 (Wasco). Public domain.