Maxwell climate

Maxwell Frost Dates and Growing Season

NOAA 1991-2020 normals for Colusa 2 Ssw, 17.2 km from Maxwell, elevation 50 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Colusa 2 Ssw. 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 February 14 and the first fall freeze around December 1, a growing season of about 293 days.

Median at 36°F
last March 31, first November 12
Median at 32°F
last February 14, first December 1
Median at 28°F
last January 8, first December 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°FApr 22Apr 15Apr 9Apr 5Mar 31Mar 24Mar 14Mar 4Feb 21
32°FMar 31Mar 13Feb 28Feb 22Feb 14Feb 5Jan 27Jan 16Jan 2
28°FFeb 20Feb 5Jan 22Jan 14Jan 8Jan 2Dec 29Dec 21Dec 11
24°FJan 27Jan 14Jan 6Jan 2Dec 31Dec 24Dec 17Dec 12Dec 5
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 28Nov 2Nov 5Nov 9Nov 12Nov 16Nov 20Nov 24Nov 30
32°FNov 11Nov 17Nov 23Nov 27Dec 1Dec 4Dec 8Dec 13Dec 26
28°FNov 24Dec 1Dec 6Dec 10Dec 15Dec 19Dec 28Jan 2Jan 17
24°FDec 2Dec 8Dec 12Dec 16Dec 22Dec 29Jan 2Jan 6Jan 22
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°F269253243235228221214208198
32°F334322312303293283271256240
28°F365365358350342337331322306
24°F365365365365365365365364347
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
98% of years
28°F or colder
75% of years
24°F or colder
21% 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
2,587
Cooling degree days, base 65°F
1,329
Growing degree days, base 40°F
7,880
Growing degree days, base 45°F
6,134
Growing degree days, base 50°F
4,582
Growing degree days, base 55°F
3,279
Growing degree days, base 60°F
2,204

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January577016
February402065
March3072177
April17922296
May56126535
June7261704
July0346811
August0307772
September9212653
October10153418
November3621121
December586017

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 17.2 km from Maxwell. 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 USC00041948 (Colusa 2 Ssw). Public domain.