Forks climate

Forks Frost Dates and Growing Season

NOAA 1991-2020 normals for Forks 1 E, 2.4 km from Forks, elevation 350 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Forks 1 E. 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 26 and the first fall freeze around October 25, a growing season of about 182 days.

Median at 36°F
last May 14, first October 5
Median at 32°F
last April 26, first October 25
Median at 28°F
last March 27, first November 15

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 31May 24May 21May 16May 14May 10May 6May 2Apr 28
32°FMay 10May 5May 1Apr 29Apr 26Apr 22Apr 18Apr 13Apr 5
28°FApr 21Apr 14Apr 6Mar 31Mar 27Mar 22Mar 14Mar 6Feb 27
24°FMar 22Mar 9Mar 1Feb 26Feb 19Feb 13Feb 1Jan 20Dec 30
20°FFeb 22Feb 12Jan 31Jan 20Jan 9Dec 31Dec 18Dec 12Dec 2
16°FFeb 12Jan 23Jan 5Dec 30Dec 21Dec 14Dec 11Dec 6Nov 30

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 20Sep 26Sep 30Oct 2Oct 5Oct 8Oct 12Oct 17Oct 24
32°FOct 6Oct 12Oct 17Oct 21Oct 25Oct 29Nov 1Nov 7Nov 15
28°FOct 23Nov 1Nov 5Nov 10Nov 15Nov 19Nov 25Dec 1Dec 9
24°FNov 8Nov 18Nov 24Nov 29Dec 4Dec 10Dec 18Dec 31Jan 16
20°FNov 22Dec 1Dec 7Dec 12Dec 19Dec 30Jan 7Jan 22Feb 11
16°FNov 28Dec 1Dec 8Dec 13Dec 17Dec 24Jan 3Jan 17Feb 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°F168159154150145140135130121
32°F210200192187182177172166158
28°F274259248239231225218211200
24°F347326316306297288278266253
20°F365365365365354343334324309
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
97% of years
20°F or colder
60% of years
16°F or colder
15% 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
5,384
Cooling degree days, base 65°F
56
Growing degree days, base 40°F
4,007
Growing degree days, base 45°F
2,588
Growing degree days, base 50°F
1,507
Growing degree days, base 55°F
732
Growing degree days, base 60°F
247

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January75202
February64503
March637010
April501038
May3562132
June2338226
July12420361
August10520380
September1946264
October428081
November629011
December78102

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 2.4 km from Forks. 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 USC00452914 (Forks 1 E). Public domain.