Stockton climate

Stockton Frost Dates and Growing Season

NOAA 1991-2020 normals for Webster Dam, 13.8 km from Stockton, elevation 1863 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Webster Dam. 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 30 and the first fall freeze around October 12, a growing season of about 165 days.

Median at 36°F
last May 8, first October 2
Median at 32°F
last April 30, first October 12
Median at 28°F
last April 19, first October 21

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 24May 18May 14May 11May 8May 6May 3Apr 30Apr 25
32°FMay 13May 9May 5May 2Apr 30Apr 27Apr 23Apr 20Apr 13
28°FMay 4Apr 30Apr 25Apr 22Apr 19Apr 16Apr 12Apr 8Apr 3
24°FApr 26Apr 19Apr 15Apr 11Apr 7Apr 4Apr 1Mar 28Mar 22
20°FApr 16Apr 8Apr 4Mar 31Mar 28Mar 24Mar 20Mar 15Mar 9
16°FApr 4Mar 30Mar 24Mar 20Mar 16Mar 13Mar 8Mar 4Feb 28

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°FSep 18Sep 23Sep 27Sep 30Oct 2Oct 5Oct 7Oct 10Oct 14
32°FSep 27Oct 2Oct 6Oct 10Oct 12Oct 14Oct 17Oct 19Oct 23
28°FOct 7Oct 12Oct 16Oct 19Oct 21Oct 23Oct 26Oct 30Nov 3
24°FOct 17Oct 22Oct 25Oct 28Nov 1Nov 2Nov 6Nov 9Nov 14
20°FOct 25Oct 30Nov 2Nov 5Nov 8Nov 11Nov 15Nov 20Nov 26
16°FNov 2Nov 7Nov 11Nov 15Nov 20Nov 23Nov 27Dec 1Dec 5

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°F165159154150146142138133125
32°F184177172168165160156151144
28°F206198193188184180176170164
24°F227219214209205200195190181
20°F250241236230225221216210200
16°F272264257251246240234229221

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
5,367
Cooling degree days, base 65°F
1,352
Growing degree days, base 40°F
6,224
Growing degree days, base 45°F
4,970
Growing degree days, base 50°F
3,865
Growing degree days, base 55°F
2,895
Growing degree days, base 60°F
2,059

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,10001
February90807
March680154
April38712162
May15281403
June14273710
July1435899
August4366828
September66163550
October34020213
November694138
December1,02102

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 13.8 km from Stockton. 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 USC00148648 (Webster Dam). Public domain.