Keizer climate

Keizer Frost Dates and Growing Season

NOAA 1991-2020 normals for Salem Mcnary Fld, 9.7 km from Keizer, elevation 205 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Salem Mcnary Fld. 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 April 3 and the first fall freeze around November 1, a growing season of about 212 days.

Median at 36°F
last April 30, first October 18
Median at 32°F
last April 3, first November 1
Median at 28°F
last March 2, first November 22

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 16May 9May 5May 2Apr 30Apr 27Apr 25Apr 20Apr 14
32°FApr 27Apr 19Apr 13Apr 7Apr 3Mar 31Mar 26Mar 20Mar 10
28°FMar 30Mar 21Mar 14Mar 8Mar 2Feb 25Feb 20Feb 15Jan 31
24°FFeb 27Feb 20Feb 14Feb 5Jan 27Jan 18Jan 7Jan 1Dec 18
20°FFeb 15Feb 1Jan 18Jan 6Dec 31Dec 25Dec 17Dec 11Dec 2
16°FFeb 13Jan 17Jan 2Dec 30Dec 25Dec 21Dec 14Dec 11Dec 5

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 2Oct 7Oct 11Oct 15Oct 18Oct 21Oct 25Oct 28Nov 2
32°FOct 16Oct 22Oct 26Oct 29Nov 1Nov 6Nov 10Nov 16Nov 23
28°FOct 30Nov 5Nov 10Nov 14Nov 22Nov 26Dec 1Dec 8Dec 17
24°FNov 12Nov 23Nov 29Dec 4Dec 10Dec 15Dec 23Dec 31Jan 16
20°FNov 27Dec 2Dec 7Dec 12Dec 19Dec 25Dec 30Jan 6Jan 30
16°FDec 4Dec 9Dec 12Dec 17Dec 21Dec 28Dec 30Jan 9Feb 11

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°F193186181175171167163157149
32°F245234225218212207200194183
28°F304290279272264257248237227
24°F358345335325318309301290274
20°F365365365365361350342333319
16°F365365365365365365365365351

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
93% of years
20°F or colder
53% of years
16°F or colder
16% 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
4,340
Cooling degree days, base 65°F
401
Growing degree days, base 40°F
5,335
Growing degree days, base 45°F
3,809
Growing degree days, base 50°F
2,568
Growing degree days, base 55°F
1,612
Growing degree days, base 60°F
895

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January71009
February588010
March541031
April412183
May23911243
June10839381
July15149598
August16146595
September8254422
October3322159
November561030
December73608

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 9.7 km from Keizer. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00024232 (Salem Mcnary Fld). Public domain.