Grays Harbor County climate

Grays Harbor County Frost Dates and Growing Season

NOAA 1991-2020 normals for Humptulips Salmon Hatchery, 15.8 km from Grays Harbor County, elevation 140 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Humptulips Salmon Hatchery. 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 22, a growing season of about 180 days.

Median at 36°F
last May 16, first October 3
Median at 32°F
last April 26, first October 22
Median at 28°F
last March 27, first November 13

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°FJun 3May 29May 24May 20May 16May 12May 6May 2Apr 28
32°FMay 15May 7May 3Apr 30Apr 26Apr 21Apr 16Apr 9Mar 31
28°FApr 22Apr 11Apr 5Mar 31Mar 27Mar 20Mar 13Mar 3Feb 21
24°FMar 19Mar 7Feb 28Feb 22Feb 16Feb 7Jan 19Dec 31Dec 12
20°FFeb 22Feb 11Jan 29Jan 14Jan 2Dec 24Dec 14Dec 7Nov 30
16°FJan 28Jan 13Dec 31Dec 25Dec 20Dec 15Dec 11Dec 5Dec 1

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 16Sep 24Sep 28Oct 1Oct 3Oct 7Oct 10Oct 15Oct 22
32°FOct 3Oct 9Oct 14Oct 19Oct 22Oct 26Oct 30Nov 4Nov 15
28°FOct 21Oct 28Nov 1Nov 6Nov 13Nov 20Nov 28Dec 4Dec 15
24°FNov 7Nov 16Nov 24Dec 1Dec 7Dec 14Dec 24Jan 2Jan 29
20°FNov 19Nov 30Dec 3Dec 10Dec 16Dec 24Jan 1Jan 16Feb 10
16°FNov 29Dec 3Dec 8Dec 12Dec 18Dec 22Dec 29Jan 10Jan 28

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°F167159152147141136131125118
32°F212199192185180175168162152
28°F274260250241233225216208196
24°F354334321311302290277266250
20°F365365365365358343334325310
16°F365365365365365365365364341

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
56% of years
16°F or colder
21% 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
5,937
Cooling degree days, base 65°F
27
Growing degree days, base 40°F
3,473
Growing degree days, base 45°F
2,144
Growing degree days, base 50°F
1,176
Growing degree days, base 55°F
505
Growing degree days, base 60°F
137

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January77401
February68501
March68205
April561021
May409297
June2854173
July17610299
August1598315
September2533204
October484054
November66606
December80401

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 15.8 km from Grays Harbor County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00453826 (Humptulips Salmon Hatchery). Public domain.