Dixon climate

Dixon Frost Dates and Growing Season

NOAA 1991-2020 normals for Iberia, 22.4 km from Dixon, elevation 938 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Iberia. 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 8 and the first fall freeze around October 28, a growing season of about 200 days.

Median at 36°F
last April 22, first October 18
Median at 32°F
last April 8, first October 28
Median at 28°F
last March 30, first November 6

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 7May 3Apr 29Apr 26Apr 22Apr 19Apr 16Apr 11Apr 7
32°FApr 26Apr 20Apr 15Apr 11Apr 8Apr 6Apr 3Mar 31Mar 26
28°FApr 14Apr 8Apr 5Apr 2Mar 30Mar 26Mar 23Mar 18Mar 12
24°FApr 3Mar 30Mar 25Mar 22Mar 18Mar 15Mar 11Mar 7Mar 1
20°FMar 24Mar 18Mar 14Mar 10Mar 7Mar 4Feb 28Feb 24Feb 18
16°FMar 16Mar 10Mar 6Mar 3Feb 28Feb 24Feb 19Feb 14Feb 5

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 9Oct 12Oct 16Oct 18Oct 21Oct 23Oct 26Oct 30
32°FOct 15Oct 20Oct 22Oct 25Oct 28Oct 30Nov 1Nov 4Nov 9
28°FOct 24Oct 30Nov 1Nov 4Nov 6Nov 9Nov 12Nov 16Nov 22
24°FNov 2Nov 6Nov 9Nov 13Nov 16Nov 20Nov 24Nov 29Dec 5
20°FNov 8Nov 14Nov 19Nov 23Nov 27Dec 1Dec 5Dec 10Dec 17
16°FNov 16Nov 24Nov 29Dec 3Dec 7Dec 12Dec 18Dec 22Dec 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°F198191186182177173169164158
32°F220213209204200196191187179
28°F243236231226221217213207201
24°F268258253247242238234228221
20°F289279273268263258252246238
16°F310301293287282278272266255

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
100% of years
20°F or colder
100% of years
16°F or colder
100% 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
4,760
Cooling degree days, base 65°F
1,315
Growing degree days, base 40°F
6,530
Growing degree days, base 45°F
5,204
Growing degree days, base 50°F
4,024
Growing degree days, base 55°F
2,991
Growing degree days, base 60°F
2,093

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,05602
February822017
March621153
April31120216
May10198466
June4253699
July0393858
August1356821
September48146548
October27342272
November603668
December92006

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 22.4 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 USC00234136 (Iberia). Public domain.