Mountain Ranch climate

Mountain Ranch Frost Dates and Growing Season

NOAA 1991-2020 normals for Calaveras Big Trees, 20.8 km from Mountain Ranch, elevation 4695 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Calaveras Big Trees. 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 May 7 and the first fall freeze around October 28, a growing season of about 169 days.

Median at 36°F
last May 30, first October 11
Median at 32°F
last May 7, first October 28
Median at 28°F
last April 18, first November 14

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°FJun 14Jun 8Jun 4Jun 1May 30May 25May 20May 14May 7
32°FMay 31May 25May 18May 13May 7May 2Apr 29Apr 24Apr 18
28°FMay 12May 2Apr 28Apr 22Apr 18Apr 14Apr 10Apr 5Mar 28
24°FApr 20Apr 13Apr 8Apr 2Mar 27Mar 19Mar 13Mar 4Feb 19
20°FMar 31Mar 16Mar 6Feb 28Feb 20Feb 13Feb 4Jan 23Jan 5
16°FFeb 28Feb 19Feb 8Jan 31Jan 22Jan 13Jan 5Dec 27Dec 15

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 24Sep 29Oct 3Oct 6Oct 11Oct 15Oct 19Oct 24Nov 1
32°FOct 5Oct 12Oct 18Oct 23Oct 28Nov 1Nov 5Nov 9Nov 16
28°FOct 23Nov 1Nov 5Nov 10Nov 14Nov 19Nov 23Nov 29Dec 5
24°FNov 6Nov 16Nov 23Nov 28Dec 3Dec 6Dec 11Dec 16Dec 23
20°FNov 24Dec 3Dec 9Dec 16Dec 21Dec 27Jan 2Jan 17Feb 1
16°FDec 4Dec 14Dec 22Dec 29Jan 3Jan 12Jan 21Feb 1Feb 12

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°F165156149142136130125119111
32°F199190183175169164157149139
28°F241229221214207201193186175
24°F289274265257249242234224210
20°F355335322310301293282272258
16°F365365365365356344333320305

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
97% of years
16°F or colder
58% 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
5,640
Cooling degree days, base 65°F
319
Growing degree days, base 40°F
4,366
Growing degree days, base 45°F
3,155
Growing degree days, base 50°F
2,183
Growing degree days, base 55°F
1,396
Growing degree days, base 60°F
770

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January84601
February75902
March76707
April615033
May4035146
June15838342
July27123561
August30103538
September12843372
October3797155
November654026
December87301

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 20.8 km from Mountain Ranch. 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 USC00041277 (Calaveras Big Trees). Public domain.