Salton City Frost Dates and Growing Season

NOAA 1991-2020 normals for Ocotillo Wells 2W, 25.4 km from Salton City, elevation 390 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ocotillo Wells 2W. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

A freeze (32°F or colder) happens in only 17 percent of years at Ocotillo Wells 2W, so there is no typical freeze season.

Median at 36°F: last January 5, first December 26
Median at 32°F: last January 7, first January 4

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 12	Jan 30	Jan 21	Jan 11	Jan 5	Dec 31	Dec 28	Dec 19	Dec 11
32°F	Feb 7	Jan 27	Jan 15	Jan 11	Jan 7	Jan 1	Dec 28	Dec 17	Dec 12
28°F	–	–	–	–	–	–	–	–	–
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	Dec 3	Dec 11	Dec 15	Dec 22	Dec 26	Dec 29	Jan 2	Jan 9	Jan 25
32°F	Dec 12	Dec 16	Dec 25	Dec 31	Jan 4	Jan 9	Jan 12	Jan 23	Feb 4
28°F	–	–	–	–	–	–	–	–	–
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	365	365	365	365	359	352	346	338	326
32°F	365	365	365	365	365	365	365	365	354
28°F	365	365	365	365	365	365	365	365	365
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: 60% of years
32°F or colder: 17% of years
28°F or colder: 2% of years
24°F or colder: 0% 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: 674
Cooling degree days, base 65°F: 4,928
Growing degree days, base 40°F: 13,379
Growing degree days, base 45°F: 11,556
Growing degree days, base 50°F: 9,743
Growing degree days, base 55°F: 7,985
Growing degree days, base 60°F: 6,356

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	201	7	278
February	116	45	350
March	46	161	580
April	11	267	707
May	2	512	975
June	0	717	1,167
July	0	952	1,417
August	0	950	1,415
September	0	747	1,197
October	3	440	902
November	59	124	515
December	237	8	241

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 25.4 km from Salton City. 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 USC00046386 (Ocotillo Wells 2W). Public domain.