Inyo County Frost Dates and Growing Season

NOAA 1991-2020 normals for Stovepipe Wells 1 Sw, 25.8 km from Inyo County, elevation 84 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Stovepipe Wells 1 Sw. 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 4 and the first fall freeze around December 22, a growing season of about 352 days.

Median at 36°F: last January 19, first December 10
Median at 32°F: last January 4, first December 22
Median at 28°F: last December 31, first December 28

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	Feb 5	Jan 31	Jan 27	Jan 22	Jan 19	Jan 15	Jan 12	Jan 7	Dec 31
32°F	Jan 23	Jan 15	Jan 11	Jan 8	Jan 4	Jan 1	Dec 28	Dec 24	Dec 16
28°F	Jan 18	Jan 10	Jan 5	Jan 3	Dec 31	Dec 27	Dec 22	Dec 17	Dec 12
24°F	–	–	–	–	–	–	–	–	–
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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	Nov 28	Dec 1	Dec 4	Dec 7	Dec 10	Dec 13	Dec 16	Dec 21	Dec 27
32°F	Dec 6	Dec 10	Dec 14	Dec 18	Dec 22	Dec 25	Dec 28	Jan 1	Jan 8
28°F	Dec 11	Dec 16	Dec 20	Dec 24	Dec 28	Jan 1	Jan 4	Jan 7	Jan 14
24°F	–	–	–	–	–	–	–	–	–
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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	348	340	335	330	325	321	316	310	303
32°F	365	365	361	357	352	347	344	338	331
28°F	365	365	365	365	365	365	365	365	356
24°F	365	365	365	365	365	365	365	365	365
20°F	365	365	365	365	365	365	365	365	365
16°F	365	365	365	365	365	365	365	365	365

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder: 99% of years
32°F or colder: 75% of years
28°F or colder: 21% of years
24°F or colder: 1% 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: 1,119
Cooling degree days, base 65°F: 5,533
Growing degree days, base 40°F: 13,540
Growing degree days, base 45°F: 11,722
Growing degree days, base 50°F: 9,958
Growing degree days, base 55°F: 8,317
Growing degree days, base 60°F: 6,844

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	354	1	135
February	166	18	276
March	44	138	559
April	5	338	783
May	0	646	1,111
June	0	919	1,369
July	0	1,158	1,623
August	0	1,090	1,555
September	0	802	1,252
October	5	374	834
November	136	49	366
December	409	0	95

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

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00053139 (Stovepipe Wells 1 Sw). Public domain.