Wilsonville climate

Wilsonville Frost Dates and Growing Season

NOAA 1991-2020 normals for Childersburg Wtp, 14.3 km from Wilsonville, elevation 418 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Childersburg Wtp. 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 March 31 and the first fall freeze around November 2, a growing season of about 216 days.

Median at 36°F
last April 11, first October 25
Median at 32°F
last March 31, first November 2
Median at 28°F
last March 16, first November 12

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°FApr 27Apr 22Apr 18Apr 15Apr 11Apr 8Apr 4Mar 31Mar 26
32°FApr 16Apr 9Apr 6Apr 3Mar 31Mar 27Mar 23Mar 18Mar 10
28°FApr 4Mar 30Mar 25Mar 21Mar 16Mar 12Mar 6Feb 28Feb 23
24°FMar 21Mar 15Mar 10Mar 4Feb 28Feb 23Feb 18Feb 12Jan 31
20°FMar 14Mar 3Feb 24Feb 16Feb 9Feb 3Jan 30Jan 24Jan 13
16°FMar 4Feb 17Feb 5Feb 1Jan 27Jan 23Jan 17Jan 11Dec 31

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°FOct 12Oct 17Oct 19Oct 22Oct 25Oct 27Oct 30Nov 2Nov 5
32°FOct 20Oct 25Oct 28Oct 31Nov 2Nov 4Nov 7Nov 11Nov 16
28°FOct 31Nov 3Nov 6Nov 8Nov 12Nov 16Nov 20Nov 26Dec 3
24°FNov 8Nov 13Nov 18Nov 22Nov 27Dec 1Dec 5Dec 12Dec 25
20°FNov 21Nov 29Dec 4Dec 9Dec 16Dec 25Jan 1Jan 6Jan 17
16°FDec 5Dec 16Dec 27Jan 1Jan 5Jan 10Jan 16Jan 25Feb 5

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°F216208203199195191187182176
32°F242233227221216211206202194
28°F272261255249243237231224216
24°F309297288281273266260253241
20°F341333325316306299292280267
16°F365365355347339333327315301

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
98% of years
16°F or colder
79% 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
2,342
Cooling degree days, base 65°F
2,205
Growing degree days, base 40°F
9,084
Growing degree days, base 45°F
7,410
Growing degree days, base 50°F
5,871
Growing degree days, base 55°F
4,484
Growing degree days, base 60°F
3,258

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January583276
February4125112
March26924256
April10184436
May18229676
June0405855
July0518983
August0490955
September6325769
October100105474
November33216186
December520494

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 14.3 km from Wilsonville. 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 USC00011620 (Childersburg Wtp). Public domain.