California Frost Dates & Growing Zones by City
We cover 6 California cities. In the 3 that have frost dates, typical (50%) last spring frosts fall between Jan 2 (San Jose) and Jan 14 (Fresno), and frost-free seasons run from 337 days (Fresno) to 362 days (San Jose).
On the 2023 USDA hardiness map, these cities fall in zones 9b, 10a, 10b and 11a.
NOAA computes no frost dates for Los Angeles, San Diego and San Francisco, where 32°F nights come in fewer than 1 year in 10.
Dates come from the nearest NOAA station to each city that meets our quality rules, as the methodology explains.
| City | Last frost (50%) | First frost (50%) | Season (days, 50%) | Zone 2023 | Confidence | Planting calendar |
|---|---|---|---|---|---|---|
| Los Angeles Freezes too rare for a typical frost date (NOAA) |
rare (6.7% of years) | rare | 365 | 9b–11a | High | not built (frost too rare) |
| San Diego Freezes too rare for a typical frost date (NOAA) |
rare (5.5% of years) | rare | 365 | 9b–11a | High | not built (frost too rare) |
| San Jose frost dates | Jan 2* | Dec 25* | 362 | 9b–10a | Medium | San Jose planting calendar |
| San Francisco Freezes too rare for a typical frost date (NOAA) |
rare (0.0% of years) | rare | 365 | 10a–10b | High | not built (frost too rare) |
| Fresno frost dates | Jan 14* | Dec 14* | 337 | 9b | High | Fresno planting calendar |
| Sacramento frost dates | Jan 12* | Dec 16* | 341 | 9b | High | Sacramento planting calendar |
* Not every winter reaches 32°F here; the date describes the years that do (NOAA conditional probability).
Station match, data and rules: methodology. Long-term odds, not a forecast.