Shingletown climate

Shingletown Frost Dates and Growing Season

NOAA 1991-2020 normals for Manzanita Lake, 27 km from Shingletown, elevation 5750 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Manzanita Lake. 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 June 9 and the first fall freeze around September 21, a growing season of about 102 days.

Median at 32°F
last June 9, first September 21
Median at 28°F
last May 22, first October 11

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°F–––––––––
32°FJun 27Jun 21Jun 16Jun 12Jun 9Jun 6Jun 3May 29May 21
28°FJun 10Jun 4May 31May 27May 22May 16May 12May 6Apr 30
24°FMay 23May 14May 6May 1Apr 29Apr 26Apr 22Apr 18Apr 13
20°FMay 5Apr 27Apr 22Apr 18Apr 16Apr 13Apr 10Apr 6Apr 2
16°FApr 23Apr 16Apr 12Apr 8Apr 5Apr 1Mar 25Mar 16Mar 10

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°F–––––––––
32°FSep 1Sep 6Sep 11Sep 16Sep 21Sep 26Sep 30Oct 4Oct 11
28°FSep 18Sep 28Oct 2Oct 7Oct 11Oct 15Oct 19Oct 24Oct 31
24°FOct 7Oct 16Oct 21Oct 26Oct 29Nov 1Nov 5Nov 9Nov 14
20°FOct 26Nov 1Nov 4Nov 8Nov 11Nov 15Nov 18Nov 22Nov 27
16°FNov 6Nov 12Nov 16Nov 19Nov 23Nov 26Nov 30Dec 3Dec 9

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°F928277706458524537
32°F12711911310710297918373
28°F170161152146141134129122112
24°F205197191186181175169161150
20°F230223217213208203197192184
16°F261251244239234228223216206

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
7,527
Cooling degree days, base 65°F
84
Growing degree days, base 40°F
2,986
Growing degree days, base 45°F
2,043
Growing degree days, base 50°F
1,295
Growing degree days, base 55°F
710
Growing degree days, base 60°F
299

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,04000
February93100
March92500
April78405
May531175
June3019193
July11540393
August13328361
September2627222
October587045
November85101
December1,06600

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 km from Shingletown. 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 USC00045311 (Manzanita Lake). Public domain.