Dixon climate

Dixon Frost Dates and Growing Season

NOAA 1991-2020 normals for Davis 2 Wsw Exp Farm, 10.7 km from Dixon, elevation 60 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Davis 2 Wsw Exp Farm. 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 10 and the first fall freeze around December 1, a growing season of about 295 days.

Median at 36°F
last March 22, first November 16
Median at 32°F
last February 10, first December 1
Median at 28°F
last January 6, first December 18

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 16Apr 9Apr 3Mar 29Mar 22Mar 16Mar 9Mar 3Feb 22
32°FMar 11Mar 2Feb 25Feb 18Feb 10Feb 2Jan 27Jan 16Dec 31
28°FFeb 8Jan 30Jan 22Jan 15Jan 6Dec 31Dec 28Dec 23Dec 14
24°FJan 24Jan 13Jan 6Dec 31Dec 30Dec 26Dec 23Dec 15Dec 9
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°FNov 1Nov 5Nov 9Nov 12Nov 16Nov 19Nov 23Nov 26Dec 1
32°FNov 13Nov 19Nov 24Nov 28Dec 1Dec 4Dec 9Dec 15Dec 27
28°FNov 29Dec 4Dec 8Dec 12Dec 18Dec 21Dec 29Jan 4Jan 18
24°FDec 5Dec 12Dec 16Dec 21Dec 26Dec 30Jan 2Jan 9Jan 20
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°F272260250243236229222215206
32°F334323313304295286277268256
28°F365365358350344339334326312
24°F365365365365365365365359344
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
73% of years
24°F or colder
26% of years
20°F or colder
1% 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
2,501
Cooling degree days, base 65°F
1,268
Growing degree days, base 40°F
7,901
Growing degree days, base 45°F
6,142
Growing degree days, base 50°F
4,562
Growing degree days, base 55°F
3,237
Growing degree days, base 60°F
2,146

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January560019
February396068
March3092175
April18420290
May63104507
June10226666
July1320784
August1297761
September7226669
October8072458
November3332143
December560023

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 10.7 km from Dixon. 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 USC00042294 (Davis 2 Wsw Exp Farm). Public domain.