San Lorenzo, 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 Lorenzo compares
- In a typical year, frost nights in San Lorenzo fall between December 25 and January 2. In 1 year in 10 the first frost comes as early as December 6, or the last frost as late as January 27.
- San Lorenzo shares its weather station with San Leandro, CA, 3 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 13 |
| 50% (median) | January 2 |
| 10% (safe for tender plants) | January 27 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | December 6 |
| 50% (median) | December 25 |
| 90% (late) | January 20 |
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 Lorenzo, 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 Hayward Air Terminal, CA weather station, 3 km away (elevation 43 ft (13 m)).
Frost dates near San Lorenzo
- San Leandro Jan 2 · Dec 25
- Castro Valley Jan 2 · Dec 25
- Hayward Jan 2 · Dec 25
- Union City Jan 7 · Dec 22
- Alameda Jan 7 · Dec 23
- Oakland rare frost
- Moraga Mar 8 · Dec 22
- Canyon Jan 3 · Jan 1
- Newark Jan 7 · Dec 22
- Fremont Jan 7 · Dec 22
Frequently asked questions
When is the last frost in San Lorenzo, CA?
The median last spring frost in San Lorenzo, CA is January 2. There is still about a 10% chance of frost after January 27, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in San Lorenzo, CA?
The median first fall frost is December 25, with about a 10% chance of frost before December 6.
How long is the growing season in San Lorenzo, CA?
About 357 days between the median last spring frost and first fall frost.
What planting zone is San Lorenzo, CA?
San Lorenzo, CA is in USDA hardiness zone 10a.