Brier climate

Brier Frost Dates and Growing Season

NOAA 1991-2020 normals for Seattle Sand Pt Wsfo, 11 km from Brier, elevation 60 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Seattle Sand Pt Wsfo. 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 8 and the first fall freeze around November 23, a growing season of about 259 days.

Median at 36°F
last April 4, first November 5
Median at 32°F
last March 8, first November 23
Median at 28°F
last February 11, first December 11

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 26Apr 18Apr 12Apr 7Apr 4Apr 1Mar 28Mar 23Mar 17
32°FMar 29Mar 21Mar 16Mar 11Mar 8Mar 3Feb 27Feb 23Feb 13
28°FMar 1Feb 25Feb 21Feb 16Feb 11Feb 2Jan 24Jan 9Dec 27
24°FFeb 20Feb 11Feb 3Jan 24Jan 9Jan 1Dec 22Dec 12Dec 3
20°FFeb 13Jan 31Jan 6Dec 30Dec 23Dec 15Dec 11Dec 5Nov 29
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 24Oct 28Oct 31Nov 2Nov 5Nov 8Nov 12Nov 16Nov 22
32°FNov 4Nov 10Nov 15Nov 19Nov 23Nov 27Dec 1Dec 6Dec 16
28°FNov 17Nov 25Dec 1Dec 5Dec 11Dec 16Dec 24Jan 1Jan 17
24°FNov 27Dec 2Dec 9Dec 15Dec 24Jan 1Jan 8Jan 24Feb 8
20°FNov 28Dec 4Dec 9Dec 14Dec 20Dec 27Jan 5Jan 28Feb 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°F237230224219215210205199191
32°F289277270265259253248241231
28°F348334324316308302293283273
24°F365365365365353340332323312
20°F365365365365365365365365338
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
96% of years
24°F or colder
59% of years
20°F or colder
16% 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
4,483
Cooling degree days, base 65°F
211
Growing degree days, base 40°F
4,967
Growing degree days, base 45°F
3,424
Growing degree days, base 50°F
2,207
Growing degree days, base 55°F
1,298
Growing degree days, base 60°F
627

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January70403
February60503
March572018
April426063
May2584215
June12518344
July3178512
August2386529
September10724368
October3540132
November558020
December72102

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 11 km from Brier. 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 USW00094290 (Seattle Sand Pt Wsfo). Public domain.