Fieldbrook climate

Fieldbrook Frost Dates and Growing Season

NOAA 1991-2020 normals for Arcata Eureka AP, 6.2 km from Fieldbrook, elevation 200 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Arcata Eureka AP. 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 8 and the first fall freeze around November 30, a growing season of about 262 days.

Median at 36°F
last April 24, first November 1
Median at 32°F
last March 8, first November 30
Median at 28°F
last January 20, first December 24

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 15May 7May 1Apr 28Apr 24Apr 18Apr 12Apr 6Mar 28
32°FApr 15Apr 5Mar 28Mar 19Mar 8Feb 26Feb 19Feb 4Jan 13
28°FFeb 26Feb 14Feb 3Jan 28Jan 20Jan 9Jan 1Dec 25Dec 14
24°FJan 28Jan 18Jan 6Dec 31Dec 29Dec 26Dec 22Dec 16Dec 11
20°F–––––––––
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 11Oct 17Oct 21Oct 26Nov 1Nov 3Nov 8Nov 14Nov 24
32°FNov 1Nov 8Nov 15Nov 22Nov 30Dec 4Dec 10Dec 18Jan 4
28°FNov 30Dec 5Dec 11Dec 18Dec 24Dec 30Jan 7Jan 21Feb 8
24°FDec 9Dec 14Dec 20Dec 25Dec 28Dec 31Jan 5Jan 16Jan 28
20°F–––––––––
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°F227214205197190183177169158
32°F315298282271262252242231216
28°F365365365355345336327313299
24°F365365365365365365365365356
20°F365365365365365365365365365
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
99% of years
28°F or colder
67% of years
24°F or colder
14% of years
20°F or colder
2% of years
16°F or colder
0% 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
4,576
Cooling degree days, base 65°F
5
Growing degree days, base 40°F
4,561
Growing degree days, base 45°F
2,825
Growing degree days, base 50°F
1,374
Growing degree days, base 55°F
413
Growing degree days, base 60°F
54

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January513046
February459040
March495039
April443050
May3771101
June2850166
July2370228
August2211245
September2482205
October3341144
November435071
December529041

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 6.2 km from Fieldbrook. 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 USW00024283 (Arcata Eureka AP). Public domain.