Big Sur Frost Dates and Growing Season

NOAA 1991-2020 normals for Big Sur Stn, 3.5 km from Big Sur, elevation 200 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Big Sur Stn. 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 13 and the first fall freeze around December 27, a growing season of about 323 days.

Median at 36°F: last April 13, first November 28
Median at 32°F: last February 13, first December 27
Median at 28°F: last January 25, first January 6

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	May 13	May 2	Apr 27	Apr 19	Apr 13	Apr 7	Apr 1	Mar 23	Mar 6
32°F	Apr 1	Mar 22	Mar 7	Feb 25	Feb 13	Feb 2	Jan 24	Jan 9	Dec 26
28°F	Mar 21	Feb 26	Feb 10	Jan 31	Jan 25	Jan 13	Jan 2	Dec 26	Dec 17
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	Oct 27	Nov 6	Nov 13	Nov 21	Nov 28	Dec 3	Dec 8	Dec 17	Dec 31
32°F	Nov 23	Dec 4	Dec 11	Dec 20	Dec 27	Jan 3	Jan 14	Jan 29	Feb 22
28°F	Dec 10	Dec 20	Dec 28	Jan 1	Jan 6	Jan 20	Jan 30	Feb 14	Mar 18
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	275	259	244	236	226	216	206	194	179
32°F	365	359	346	334	323	311	296	282	268
28°F	365	365	365	365	365	365	365	353	331
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: 83% of years
28°F or colder: 28% of years
24°F or colder: 2% 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: 2,967
Cooling degree days, base 65°F: 212
Growing degree days, base 40°F: 6,371
Growing degree days, base 45°F: 4,563
Growing degree days, base 50°F: 2,885
Growing degree days, base 55°F: 1,525
Growing degree days, base 60°F: 641

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	421	1	90
February	367	1	88
March	352	3	138
April	296	8	170
May	232	15	249
June	141	24	333
July	95	32	401
August	76	37	426
September	96	50	404
October	161	37	341
November	295	6	173
December	437	0	72

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 3.5 km from Big Sur. 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 USC00040790 (Big Sur Stn). Public domain.