Kitsap County climate

Kitsap County Frost Dates and Growing Season

NOAA 1991-2020 normals for Bremerton, 8.3 km from Kitsap County, elevation 110 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bremerton. 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 29 and the first fall freeze around November 14, a growing season of about 227 days.

Median at 36°F
last April 25, first October 27
Median at 32°F
last March 29, first November 14
Median at 28°F
last February 27, first November 30

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 13May 6May 2Apr 29Apr 25Apr 21Apr 17Apr 13Apr 7
32°FApr 24Apr 15Apr 7Apr 2Mar 29Mar 25Mar 20Mar 13Mar 5
28°FMar 27Mar 17Mar 9Mar 1Feb 27Feb 23Feb 16Feb 10Jan 24
24°FFeb 24Feb 18Feb 13Feb 5Jan 26Jan 11Jan 2Dec 24Dec 9
20°FFeb 16Feb 9Jan 29Jan 7Dec 31Dec 22Dec 13Dec 7Dec 2
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 4Oct 13Oct 18Oct 23Oct 27Oct 30Nov 4Nov 8Nov 13
32°FOct 26Nov 2Nov 7Nov 10Nov 14Nov 17Nov 21Nov 25Dec 1
28°FNov 10Nov 17Nov 23Nov 26Nov 30Dec 3Dec 8Dec 16Dec 24
24°FNov 23Nov 28Dec 3Dec 8Dec 15Dec 23Dec 30Jan 7Feb 1
20°FNov 27Dec 3Dec 6Dec 11Dec 18Dec 25Jan 1Jan 23Feb 9
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°F210201195189183178173167158
32°F257247239232227221214207197
28°F314300289281273267260251239
24°F365358347338330322314304291
20°F365365365365365364352338324
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
100% of years
24°F or colder
87% of years
20°F or colder
42% of years
16°F or colder
5% 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
4,825
Cooling degree days, base 65°F
193
Growing degree days, base 40°F
4,658
Growing degree days, base 45°F
3,200
Growing degree days, base 50°F
2,058
Growing degree days, base 55°F
1,195
Growing degree days, base 60°F
568

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January74102
February63702
March598018
April450060
May2806201
June15020320
July5067482
August4077502
September12823345
October3831111
November602014
December76601

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 8.3 km from Kitsap County. 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 USC00450872 (Bremerton). Public domain.