Glenn County climate

Glenn County Frost Dates and Growing Season

NOAA 1991-2020 normals for Stony Gorge Rsvr, 12.3 km from Glenn County, elevation 800 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Stony Gorge Rsvr. 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 5 and the first fall freeze around November 13, a growing season of about 220 days.

Median at 36°F
last April 24, first October 31
Median at 32°F
last April 5, first November 13
Median at 28°F
last March 1, first November 29

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 12May 4Apr 30Apr 28Apr 24Apr 21Apr 18Apr 14Apr 9
32°FApr 24Apr 18Apr 14Apr 9Apr 5Mar 31Mar 26Mar 18Mar 8
28°FApr 5Mar 26Mar 15Mar 7Mar 1Feb 23Feb 15Feb 2Jan 16
24°FFeb 28Feb 13Feb 1Jan 24Jan 13Jan 5Dec 31Dec 25Dec 15
20°FFeb 8Jan 23Jan 11Jan 5Dec 31Dec 28Dec 22Dec 16Dec 10
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°FOct 13Oct 21Oct 25Oct 29Oct 31Nov 2Nov 5Nov 8Nov 13
32°FOct 29Nov 2Nov 6Nov 10Nov 13Nov 16Nov 20Nov 24Nov 29
28°FNov 8Nov 15Nov 20Nov 24Nov 29Dec 1Dec 5Dec 9Dec 19
24°FNov 21Nov 29Dec 4Dec 9Dec 13Dec 18Dec 24Jan 1Jan 17
20°FDec 5Dec 10Dec 14Dec 21Dec 27Dec 30Jan 3Jan 15Jan 29
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°F210203198192188183178172163
32°F250238232225220215210204194
28°F317302290279271263254244233
24°F365357348341334328318307291
20°F365365365365365365357349336
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
100% of years
28°F or colder
100% of years
24°F or colder
86% of years
20°F or colder
39% of years
16°F or colder
8% 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
3,190
Cooling degree days, base 65°F
1,364
Growing degree days, base 40°F
7,337
Growing degree days, base 45°F
5,674
Growing degree days, base 50°F
4,253
Growing degree days, base 55°F
3,086
Growing degree days, base 60°F
2,137

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January622012
February489034
March431092
April2865188
May11675425
June22233662
July1416880
August1363828
September16221656
October14050378
November426089
December642010

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 12.3 km from Glenn County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00048587 (Stony Gorge Rsvr). Public domain.