Gridley climate

Gridley Frost Dates and Growing Season

NOAA 1991-2020 normals for Oroville Muni AP, 15.4 km from Gridley, elevation 190 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Oroville Muni AP. 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 January 29 and the first fall freeze around December 7, a growing season of about 317 days.

Median at 36°F
last March 6, first November 24
Median at 32°F
last January 29, first December 7
Median at 28°F
last January 9, first December 27

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 1Mar 24Mar 16Mar 10Mar 6Mar 1Feb 24Feb 15Feb 4
32°FFeb 28Feb 20Feb 12Feb 3Jan 29Jan 22Jan 15Jan 6Dec 28
28°FFeb 6Jan 28Jan 21Jan 14Jan 9Jan 3Dec 31Dec 25Dec 16
24°FJan 22Jan 17Jan 12Jan 6Jan 3Jan 1Dec 31Dec 26Dec 20
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 7Nov 12Nov 16Nov 20Nov 24Nov 27Nov 30Dec 3Dec 10
32°FNov 20Nov 26Nov 30Dec 4Dec 7Dec 12Dec 18Dec 28Jan 6
28°FDec 2Dec 8Dec 16Dec 21Dec 27Jan 1Jan 6Jan 14Jan 26
24°FDec 20Dec 26Dec 30Dec 31Jan 2Jan 5Jan 12Jan 17Jan 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°F297283274267261254247240232
32°F349339332324317309302291279
28°F365365365365360353347339330
24°F365365365365365365365365361
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
95% of years
28°F or colder
57% of years
24°F or colder
12% of years
20°F or colder
0% 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
2,394
Cooling degree days, base 65°F
1,747
Growing degree days, base 40°F
8,488
Growing degree days, base 45°F
6,721
Growing degree days, base 50°F
5,120
Growing degree days, base 55°F
3,769
Growing degree days, base 60°F
2,655

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January544025
February379080
March2932185
April16628314
May47140558
June6318762
July0480945
August0428893
September5275720
October7475467
November3341143
December546029

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 15.4 km from Gridley. 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 USW00093210 (Oroville Muni AP). Public domain.