Orcutt Frost Dates and Growing Season

NOAA 1991-2020 normals for Santa Maria Public AP, 4 km from Orcutt, elevation 242 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Santa Maria Public AP. 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 February 4 and the first fall freeze around December 13, a growing season of about 315 days.

Median at 36°F: last March 22, first November 25
Median at 32°F: last February 4, first December 13
Median at 28°F: last January 5, first December 27

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	Apr 17	Apr 10	Apr 3	Mar 29	Mar 22	Mar 12	Mar 2	Feb 23	Feb 12
32°F	Mar 16	Feb 27	Feb 18	Feb 11	Feb 4	Jan 28	Jan 19	Jan 8	Dec 29
28°F	Feb 8	Jan 27	Jan 20	Jan 11	Jan 5	Dec 31	Dec 28	Dec 21	Dec 14
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 3	Nov 11	Nov 16	Nov 21	Nov 25	Nov 29	Dec 2	Dec 6	Dec 14
32°F	Nov 21	Nov 30	Dec 5	Dec 9	Dec 13	Dec 18	Dec 23	Dec 31	Jan 10
28°F	Dec 5	Dec 12	Dec 18	Dec 23	Dec 27	Dec 31	Jan 2	Jan 9	Jan 27
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	290	276	264	256	247	240	233	223	211
32°F	354	340	331	323	315	306	297	284	268
28°F	365	365	365	365	365	361	352	343	334
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: 100% of years
32°F or colder: 94% of years
28°F or colder: 48% of years
24°F or colder: 9% of years
20°F or colder: 1% 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: 2,484
Cooling degree days, base 65°F: 165
Growing degree days, base 40°F: 6,807
Growing degree days, base 45°F: 4,990
Growing degree days, base 50°F: 3,257
Growing degree days, base 55°F: 1,765
Growing degree days, base 60°F: 690

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	377	0	115
February	319	1	122
March	303	2	175
April	252	5	207
May	194	8	279
June	117	11	344
July	55	27	437
August	48	31	448
September	59	40	431
October	121	34	378
November	243	8	221
December	397	0	100

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 4 km from Orcutt. 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 USW00023273 (Santa Maria Public AP). Public domain.