San Bruno, CA frost dates
Frost is light and occasional here — typically a few cold nights around midwinter (about 1 a year). Cover tender plants when frost is forecast.
How San Bruno compares
- In a typical year, frost nights in San Bruno fall between January 10 and January 11. In 1 year in 10 the first frost comes as early as December 22, or the last frost as late as February 12.
- Compared with South San Francisco, CA, 4 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 11 |
| 10% (safe for tender plants) | February 12 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | December 22 |
| 50% (median) | January 10 |
| 90% (late) | February 5 |
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
San Bruno, 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 Pacifica 4 Sse, CA weather station, 5 km away (elevation 476 ft (145 m)).
Frost dates near San Bruno
- South San Francisco Dec 29 · Dec 26
- Millbrae Dec 29 · Dec 26
- Pacifica Jan 11 · Jan 10
- Brisbane Dec 29 · Dec 26
- Burlingame Dec 29 · Dec 26
- Daly City Dec 30 · Dec 25
- Montara Jan 11 · Jan 10
- Moss Beach Jan 11 · Jan 10
- El Granada Feb 6 · Dec 17
- San Mateo Dec 29 · Dec 26
Frequently asked questions
When is the last frost in San Bruno, CA?
The median last spring frost in San Bruno, CA is January 11. There is still about a 10% chance of frost after February 12, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in San Bruno, CA?
The median first fall frost is January 10, with about a 10% chance of frost before December 22.
How long is the growing season in San Bruno, CA?
About 364 days between the median last spring frost and first fall frost.
What planting zone is San Bruno, CA?
San Bruno, CA is in USDA hardiness zone 10a.