Van Nuys Frost Dates and Growing Season

NOAA 1991-2020 normals for Van Nuys AP, 4.5 km from Van Nuys, elevation 770 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Van Nuys 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 22 percent of years at Van Nuys AP, so there is no typical freeze season.

Median at 36°F: last January 19, first December 22
Median at 32°F: last December 31, first December 30

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 27	Feb 15	Feb 3	Jan 27	Jan 19	Jan 11	Jan 4	Dec 30	Dec 18
32°F	Jan 27	Jan 16	Jan 8	Jan 3	Dec 31	Dec 28	Dec 22	Dec 14	Dec 9
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 1	Dec 7	Dec 12	Dec 16	Dec 22	Dec 27	Jan 1	Jan 8	Jan 23
32°F	Dec 9	Dec 14	Dec 19	Dec 25	Dec 30	Jan 1	Jan 5	Jan 13	Jan 25
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	363	354	347	340	331	320	307	292
32°F	365	365	365	365	365	365	365	361	348
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: 82% of years
32°F or colder: 22% of years
28°F or colder: 1% 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: 1,226
Cooling degree days, base 65°F: 1,837
Growing degree days, base 40°F: 9,737
Growing degree days, base 45°F: 7,914
Growing degree days, base 50°F: 6,119
Growing degree days, base 55°F: 4,441
Growing degree days, base 60°F: 2,988

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	254	10	232
February	224	11	214
March	164	29	333
April	106	58	402
May	39	116	543
June	5	215	660
July	0	395	860
August	0	434	899
September	2	348	796
October	25	173	612
November	129	43	366
December	280	5	202

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 4.5 km from Van Nuys. 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 USW00023130 (Van Nuys AP). Public domain.