Cedar Hills climate

Cedar Hills Frost Dates and Growing Season

NOAA 1991-2020 normals for Nature Park-Beaverton, 3.3 km from Cedar Hills, elevation 185 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Nature Park-Beaverton. 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 February 11 and the first fall freeze around December 5, a growing season of about 303 days.

Median at 36°F
last March 23, first November 13
Median at 32°F
last February 11, first December 5
Median at 28°F
last January 6, first December 21

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 15Apr 6Mar 31Mar 26Mar 23Mar 18Mar 11Mar 4Feb 25
32°FMar 5Feb 27Feb 22Feb 17Feb 11Feb 3Jan 25Jan 9Dec 26
28°FFeb 16Feb 6Jan 28Jan 16Jan 6Jan 1Dec 22Dec 12Dec 2
24°FFeb 11Feb 1Jan 23Jan 12Jan 1Dec 30Dec 19Dec 13Dec 4
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°FOct 26Nov 1Nov 5Nov 10Nov 13Nov 17Nov 22Nov 28Dec 4
32°FNov 11Nov 18Nov 24Nov 30Dec 5Dec 10Dec 18Dec 29Jan 12
28°FNov 24Dec 1Dec 7Dec 12Dec 21Dec 31Jan 6Jan 19Feb 5
24°FDec 2Dec 8Dec 13Dec 21Dec 30Jan 1Jan 16Jan 30Feb 5
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°F268257248241235230224217206
32°F344331319310303294284275264
28°F365365365365357345336326312
24°F365365365365365365365365342
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
56% of years
24°F or colder
15% of years
20°F or colder
4% 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
3,732
Cooling degree days, base 65°F
405
Growing degree days, base 40°F
5,841
Growing degree days, base 45°F
4,167
Growing degree days, base 50°F
2,763
Growing degree days, base 55°F
1,699
Growing degree days, base 60°F
923

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January619011
February497022
March468052
April3384133
May18521302
June9745398
July19131576
August12149601
September7854426
October2823193
November489042
December64809

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 3.3 km from Cedar Hills. 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 USC00355945 (Nature Park-Beaverton). Public domain.