Nooksack climate

Nooksack Frost Dates and Growing Season

NOAA 1991-2020 normals for Clearbrook, 4.4 km from Nooksack, elevation 64 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Clearbrook. 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 18 and the first fall freeze around October 18, a growing season of about 185 days.

Median at 36°F
last May 7, first September 29
Median at 32°F
last April 18, first October 18
Median at 28°F
last March 18, first November 7

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 22May 17May 13May 10May 7May 4May 1Apr 28Apr 23
32°FMay 5May 1Apr 27Apr 22Apr 18Apr 14Apr 8Apr 3Mar 27
28°FApr 8Apr 1Mar 26Mar 22Mar 18Mar 14Mar 8Mar 3Feb 25
24°FMar 12Mar 6Mar 1Feb 26Feb 21Feb 15Feb 5Jan 27Jan 10
20°FFeb 24Feb 17Feb 4Jan 30Jan 20Jan 11Jan 3Dec 23Dec 9
16°FFeb 1Jan 27Jan 19Jan 12Jan 7Jan 1Dec 25Dec 14Dec 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°FSep 10Sep 17Sep 22Sep 26Sep 29Oct 1Oct 4Oct 7Oct 14
32°FSep 28Oct 4Oct 8Oct 13Oct 18Oct 22Oct 28Nov 1Nov 8
28°FOct 20Oct 27Oct 31Nov 3Nov 7Nov 12Nov 18Nov 25Dec 4
24°FNov 6Nov 11Nov 18Nov 26Dec 1Dec 5Dec 12Dec 20Dec 30
20°FNov 20Nov 29Dec 3Dec 9Dec 16Dec 22Dec 30Jan 9Jan 25
16°FNov 29Dec 5Dec 11Dec 19Dec 27Jan 1Jan 7Jan 16Jan 26

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°F166158152147143139134128121
32°F215204195190185179173164155
28°F270257249241235229221214202
24°F328314304295288280273263251
20°F365358348338333325315305289
16°F365365365365363356346336328

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
86% of years
16°F or colder
51% 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
5,426
Cooling degree days, base 65°F
72
Growing degree days, base 40°F
4,135
Growing degree days, base 45°F
2,775
Growing degree days, base 50°F
1,712
Growing degree days, base 55°F
902
Growing degree days, base 60°F
341

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January84301
February68902
March64209
April476044
May2982179
June1678291
July7430422
August7527417
September1924264
October448075
November66908
December85401

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 4.4 km from Nooksack. 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 USC00451484 (Clearbrook). Public domain.