Harman US

Frost Dates for Concord, CA

Last spring frost
Jan 9
First fall frost
Dec 14
Growing season
343 days
Hardiness zone
9b

In an average year around Concord, CA, the last spring frost (32°F) is about Jan 9 and the first fall frost is about Dec 14, giving roughly a 343-day growing season. To be safe most years, wait until Dec 16 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 - Concord, CA
Frost intensity Early (10%) Average (50%) Late (90%)
Light (36°F) Mar 13 Feb 14 Jan 12
Freeze (32°F) Feb 12 Jan 9 Dec 16
Hard (28°F) Jan 19 Dec 30 Dec 10
Show full probability table (all thresholds & percentiles)
°F 10% 20% 30% 40% 50% 60% 70% 80% 90%
36°F Mar 13 Mar 2 Feb 26 Feb 20 Feb 14 Feb 8 Feb 2 Jan 24 Jan 12
32°F Feb 12 Jan 31 Jan 23 Jan 16 Jan 9 Jan 3 Dec 30 Dec 25 Dec 16
28°F Jan 19 Jan 12 Jan 5 Dec 31 Dec 30 Dec 27 Dec 22 Dec 17 Dec 10

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 - Concord, CA
Frost intensity Early (10%) Average (50%) Late (90%)
Light (36°F) Nov 14 Dec 1 Dec 26
Freeze (32°F) Nov 28 Dec 14 Jan 16
Hard (28°F) Dec 5 Dec 23 Jan 12
Show full probability table (all thresholds & percentiles)
°F 10% 20% 30% 40% 50% 60% 70% 80% 90%
36°F Nov 14 Nov 20 Nov 24 Nov 27 Dec 1 Dec 3 Dec 7 Dec 13 Dec 26
32°F Nov 28 Dec 2 Dec 6 Dec 10 Dec 14 Dec 18 Dec 25 Jan 3 Jan 16
28°F Dec 5 Dec 10 Dec 14 Dec 19 Dec 23 Dec 27 Dec 31 Jan 4 Jan 12

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: Concord Buchanan Fld, Ca, about 5.4 miles away@if(!empty($station['elevation_ft'])), at 18 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 Concord, CA?

On average, the last spring frost (32°F) around Concord, CA is about Jan 9. In cooler years it can run later, so for a safer bet many gardeners wait until Dec 16.

When is the first frost in the fall?

The first fall frost around Concord, CA typically arrives about Dec 14. 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 9 on average, or Dec 16 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 343 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 94521 Planting calendar → California frost dates →

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