Canby climate

Canby Frost Dates and Growing Season

NOAA 1991-2020 normals for N Willamette Exp Stn, 5 km from Canby, elevation 150 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for N Willamette 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 March 18 and the first fall freeze around November 13, a growing season of about 243 days.

Median at 36°F
last April 17, first October 27
Median at 32°F
last March 18, first November 13
Median at 28°F
last February 13, first December 1

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 6May 1Apr 27Apr 22Apr 17Apr 12Apr 8Apr 3Mar 29
32°FApr 10Apr 2Mar 28Mar 23Mar 18Mar 13Mar 8Mar 1Feb 22
28°FMar 10Feb 28Feb 23Feb 18Feb 13Feb 7Jan 28Jan 13Dec 30
24°FFeb 18Feb 11Feb 1Jan 22Jan 12Jan 3Dec 25Dec 15Dec 6
20°FFeb 14Feb 2Jan 23Jan 8Jan 1Dec 24Dec 17Dec 12Dec 2
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°FOct 11Oct 17Oct 20Oct 24Oct 27Oct 30Nov 1Nov 7Nov 15
32°FOct 27Nov 1Nov 5Nov 10Nov 13Nov 18Nov 23Nov 30Dec 6
28°FNov 9Nov 14Nov 21Nov 26Dec 1Dec 6Dec 13Dec 20Dec 31
24°FNov 20Nov 29Dec 6Dec 12Dec 18Dec 27Jan 2Jan 15Feb 2
20°FNov 30Dec 7Dec 12Dec 19Dec 28Jan 1Jan 11Jan 25Feb 10
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°F219209204198193188181174165
32°F275263256249243236229220210
28°F338325315306298289279271258
24°F365365362351341334326316306
20°F365365365365365365365352334
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
100% of years
28°F or colder
98% of years
24°F or colder
73% of years
20°F or colder
33% of years
16°F or colder
7% 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
4,409
Cooling degree days, base 65°F
374
Growing degree days, base 40°F
5,240
Growing degree days, base 45°F
3,717
Growing degree days, base 50°F
2,490
Growing degree days, base 55°F
1,558
Growing degree days, base 60°F
853

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January71905
February58507
March549029
April416183
May24913236
June10940381
July21132577
August19135581
September8851413
October3422151
November576022
December73606

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 km from Canby. 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 USC00356151 (N Willamette Exp Stn). Public domain.