Moorpark Frost Dates and Growing Season

NOAA 1991-2020 normals for Camarillo AP, 20 km from Moorpark, elevation 77 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Camarillo AP. 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 29 percent of years at Camarillo AP, so there is no typical freeze season.

Median at 36°F: last February 1, first December 17
Median at 32°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	Mar 9	Feb 27	Feb 18	Feb 9	Feb 1	Jan 23	Jan 12	Jan 2	Dec 24
32°F	Feb 2	Jan 18	Jan 11	Jan 4	Dec 31	Dec 27	Dec 21	Dec 15	Dec 11
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 3	Dec 9	Dec 13	Dec 17	Dec 22	Dec 27	Jan 3	Jan 22
32°F	Dec 7	Dec 13	Dec 17	Dec 22	Dec 28	Dec 31	Jan 4	Jan 12	Jan 29
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	360	347	340	331	322	311	302	289	275
32°F	365	365	365	365	365	365	365	355	344
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: 94% of years
32°F or colder: 29% of years
28°F or colder: 0% 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: 1,551
Cooling degree days, base 65°F: 643
Growing degree days, base 40°F: 8,216
Growing degree days, base 45°F: 6,392
Growing degree days, base 50°F: 4,589
Growing degree days, base 55°F: 2,918
Growing degree days, base 60°F: 1,564

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	275	11	209
February	243	8	189
March	226	7	249
April	161	14	303
May	103	20	381
June	25	51	476
July	3	132	594
August	1	163	626
September	7	142	585
October	61	66	470
November	155	26	322
December	292	5	187

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 20 km from Moorpark. 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 USW00023136 (Camarillo AP). Public domain.