Hercules, CA frost dates
Frost is light and occasional here — typically a few cold nights around midwinter (about 5 a year). Cover tender plants when frost is forecast.
How Hercules compares
- In a typical year, frost nights in Hercules fall between December 27 and January 17. In 1 year in 10 the first frost comes as early as December 4, or the last frost as late as March 4.
- Compared with Richmond, CA, 11 km away, the last frost here is 13 days later than there.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 23 |
| 50% (median) | January 17 |
| 10% (safe for tender plants) | March 4 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | December 4 |
| 50% (median) | December 27 |
| 90% (late) | February 4 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Gardening where frost is rare
Hercules, CA only freezes on a few winter nights, so the usual "plant after the last frost" rule doesn't apply. Heat and rainfall decide the seasons instead:
- Cool-season crops (lettuce, broccoli, peas, carrots) grow best from fall through late winter.
- Warm-season crops (tomatoes, peppers, beans, squash) do best planted in late winter to spring, and again in late summer for a fall crop — midsummer heat can stop tomatoes setting fruit.
- Heat lovers (okra, sweet potatoes, melons) can be planted through spring and early summer.
About these dates
Based on 1991–2020 NOAA climate normals for the Vallejo, CA weather station, 12 km away (elevation 341 ft (104 m)).
Frost dates near Hercules
- Pinole Jan 4 · Jan 2
- Rodeo Jan 17 · Dec 27
- El Sobrante Jan 4 · Jan 2
- Crockett Jan 17 · Dec 27
- San Pablo Jan 4 · Jan 2
- Port Costa Jan 17 · Dec 27
- El Cerrito Jan 3 · Jan 1
- Richmond Jan 4 · Jan 2
- Benicia Jan 17 · Dec 27
- Martinez Feb 28 · Nov 22
Frequently asked questions
When is the last frost in Hercules, CA?
The median last spring frost in Hercules, CA is January 17. There is still about a 10% chance of frost after March 4, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Hercules, CA?
The median first fall frost is December 27, with about a 10% chance of frost before December 4.
How long is the growing season in Hercules, CA?
About 344 days between the median last spring frost and first fall frost.
What planting zone is Hercules, CA?
Hercules, CA is in USDA hardiness zone 9b.