Harman US

Frost Dates for Westmorland, CA

Last spring frost
Jan 16
First fall frost
Dec 19
Growing season
335 days
Hardiness zone
9b

In an average year around Westmorland, CA, the last spring frost (32°F) is about Jan 16 and the first fall frost is about Dec 19, giving roughly a 335-day growing season. To be safe most years, wait until Dec 21 before setting out tender plants.

Last spring frost

Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.

Last spring frost - Westmorland, CA
Frost intensity Early (10%) Average (50%) Late (90%)
Light (36°F) Feb 28 Feb 10 Jan 13
Freeze (32°F) Feb 17 Jan 16 Dec 21
Hard (28°F) Feb 2 Jan 2 Dec 12
Show full probability table (all thresholds & percentiles)
°F 10% 20% 30% 40% 50% 60% 70% 80% 90%
36°F Feb 28 Feb 24 Feb 19 Feb 14 Feb 10 Feb 4 Jan 31 Jan 22 Jan 13
32°F Feb 17 Feb 7 Feb 1 Jan 24 Jan 16 Jan 10 Jan 5 Dec 31 Dec 21
28°F Feb 2 Jan 18 Jan 10 Jan 5 Jan 2 Dec 29 Dec 25 Dec 19 Dec 12

First fall frost

Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.

First fall frost - Westmorland, CA
Frost intensity Early (10%) Average (50%) Late (90%)
Light (36°F) Nov 22 Dec 6 Dec 21
Freeze (32°F) Dec 2 Dec 19 Jan 17
Hard (28°F) Dec 10 Dec 29 Jan 27
Show full probability table (all thresholds & percentiles)
°F 10% 20% 30% 40% 50% 60% 70% 80% 90%
36°F Nov 22 Nov 27 Dec 1 Dec 4 Dec 6 Dec 9 Dec 13 Dec 16 Dec 21
32°F Dec 2 Dec 7 Dec 11 Dec 15 Dec 19 Dec 23 Dec 28 Jan 3 Jan 17
28°F Dec 10 Dec 16 Dec 21 Dec 25 Dec 29 Jan 1 Jan 5 Jan 11 Jan 27

Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.

Where this data comes from

These dates are computed from the nearest official weather station with long-term records: Brawley 2 Sw, Ca, about 7.3 miles away@if(!empty($station['elevation_ft'])), at -100 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.

@endif
How we calculate these dates

Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.

Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.

Frequently asked questions

When is the last frost in Westmorland, CA?

On average, the last spring frost (32°F) around Westmorland, CA is about Jan 16. In cooler years it can run later, so for a safer bet many gardeners wait until Dec 21.

When is the first frost in the fall?

The first fall frost around Westmorland, CA typically arrives about Dec 19. Count back by a crop's days to maturity to find the latest date you can plant it.

When can I plant tomatoes and other tender crops?

Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Jan 16 on average, or Dec 21 to be safe most years.

How long is the growing season here?

The frost-free growing season (between the last spring and first fall 32°F frost) is about 335 days in a typical year.

Are these dates a forecast for this year?

No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.

Local weather for 92281 Planting calendar → California frost dates →

Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026