Langley climate

Langley Frost Dates and Growing Season

NOAA 1991-2020 normals for Everett, 17.3 km from Langley, elevation 60 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Everett. 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 24 and the first fall freeze around November 2, a growing season of about 223 days.

Median at 36°F
last April 20, first October 18
Median at 32°F
last March 24, first November 2
Median at 28°F
last March 1, first November 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°FMay 8May 3Apr 29Apr 24Apr 20Apr 15Apr 10Apr 6Mar 31
32°FApr 11Apr 4Apr 1Mar 29Mar 24Mar 21Mar 17Mar 12Mar 4
28°FMar 20Mar 14Mar 8Mar 4Mar 1Feb 26Feb 21Feb 14Jan 31
24°FFeb 28Feb 25Feb 17Feb 9Jan 31Jan 20Jan 9Jan 1Dec 15
20°FFeb 14Feb 1Jan 21Jan 8Jan 1Dec 25Dec 16Dec 9Dec 1
16°FJan 31Jan 6Jan 3Jan 1Dec 28Dec 16Dec 9Dec 6Nov 29

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 1Oct 6Oct 11Oct 15Oct 18Oct 22Oct 25Oct 30Nov 4
32°FOct 16Oct 22Oct 27Oct 31Nov 2Nov 6Nov 11Nov 17Nov 23
28°FOct 29Nov 5Nov 11Nov 16Nov 21Nov 25Nov 29Dec 4Dec 14
24°FNov 12Nov 20Nov 26Dec 1Dec 5Dec 10Dec 18Dec 28Jan 11
20°FNov 23Nov 30Dec 4Dec 9Dec 15Dec 23Dec 31Jan 6Jan 30
16°FNov 26Dec 1Dec 7Dec 11Dec 21Dec 30Jan 1Jan 5Jan 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°F209199194188183176170164154
32°F249240233228223218212206197
28°F303288279272265259252244234
24°F355340332323315308300287272
20°F365365365365356346338328315
16°F365365365365365365365365345

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
94% of years
20°F or colder
59% of years
16°F or colder
20% 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
4,824
Cooling degree days, base 65°F
135
Growing degree days, base 40°F
4,616
Growing degree days, base 45°F
3,140
Growing degree days, base 50°F
1,983
Growing degree days, base 55°F
1,109
Growing degree days, base 60°F
485

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January73604
February63103
March594019
April435065
May2692205
June13913324
July5153467
August4458479
September1599301
October403099
November600017
December76302

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 17.3 km from Langley. 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 USC00452675 (Everett). Public domain.