Clay climate

Clay Frost Dates and Growing Season

NOAA 1991-2020 normals for Lodi, 27.9 km from Clay, elevation 40 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lodi. 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 9 and the first fall freeze around December 5, a growing season of about 301 days.

Median at 36°F
last March 11, first November 19
Median at 32°F
last February 9, first December 5
Median at 28°F
last January 12, first December 20

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 20Apr 5Mar 26Mar 18Mar 11Mar 4Feb 27Feb 21Feb 9
32°FMar 7Feb 28Feb 22Feb 15Feb 9Feb 2Jan 26Jan 15Jan 2
28°FFeb 18Feb 6Jan 29Jan 19Jan 12Jan 5Dec 31Dec 26Dec 12
24°FFeb 6Jan 25Jan 16Jan 9Jan 3Dec 31Dec 29Dec 24Dec 13
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 5Nov 9Nov 14Nov 17Nov 19Nov 22Nov 25Nov 29Dec 4
32°FNov 17Nov 24Nov 29Dec 1Dec 5Dec 9Dec 14Dec 21Jan 3
28°FNov 30Dec 5Dec 10Dec 14Dec 20Dec 27Jan 1Jan 6Jan 24
24°FDec 9Dec 17Dec 25Dec 29Jan 1Jan 5Jan 11Jan 17Jan 31
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°F285272265258251244237228211
32°F339327317309301294286277264
28°F365365364356348340333322308
24°F365365365365365365365363351
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
23% 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
2,283
Cooling degree days, base 65°F
1,298
Growing degree days, base 40°F
8,148
Growing degree days, base 45°F
6,374
Growing degree days, base 50°F
4,747
Growing degree days, base 55°F
3,351
Growing degree days, base 60°F
2,207

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January522036
February360087
March2593215
April15323320
May52108521
June5230675
July0333798
August0312777
September3224671
October6964460
November3211152
December538034

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 27.9 km from Clay. 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 USC00045032 (Lodi). Public domain.