Borrego Springs Frost Dates and Growing Season

NOAA 1991-2020 normals for Borrego Desert Park, 2.7 km from Borrego Springs, elevation 810 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Borrego Desert Park. 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 45 percent of years at Borrego Desert Park, so there is no typical freeze season.

Median at 36°F: last February 3, first December 19
Median at 32°F: last January 10, first January 1

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	Mar 7	Feb 26	Feb 18	Feb 10	Feb 3	Jan 23	Jan 13	Jan 5	Dec 26
32°F	Feb 16	Feb 6	Jan 27	Jan 18	Jan 10	Jan 3	Dec 30	Dec 22	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	Nov 27	Dec 4	Dec 9	Dec 13	Dec 19	Dec 23	Dec 28	Jan 4	Jan 21
32°F	Dec 8	Dec 14	Dec 23	Dec 28	Jan 1	Jan 7	Jan 17	Jan 27	Feb 11
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	361	349	339	330	322	312	305	295	280
32°F	365	365	365	365	365	364	356	342	328
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: 93% of years
32°F or colder: 45% of years
28°F or colder: 9% 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: 880
Cooling degree days, base 65°F: 4,122
Growing degree days, base 40°F: 12,368
Growing degree days, base 45°F: 10,545
Growing degree days, base 50°F: 8,739
Growing degree days, base 55°F: 7,013
Growing degree days, base 60°F: 5,457

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	235	6	244
February	167	23	279
March	85	96	476
April	32	197	615
May	6	400	859
June	0	636	1,086
July	0	845	1,310
August	0	842	1,307
September	0	642	1,092
October	6	347	806
November	89	86	448
December	260	4	218

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 2.7 km from Borrego Springs. 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 USC00040983 (Borrego Desert Park). Public domain.