Atherton, CA frost dates
Frost is light and occasional here — typically a few cold nights around midwinter (about 6 a year). Cover tender plants when frost is forecast.
How Atherton compares
- In a typical year, frost nights in Atherton fall between December 12 and January 17. In 1 year in 10 the first frost comes as early as November 24, or the last frost as late as February 16.
- Compared with Palo Alto, CA, 5 km away, the last frost here is 15 days earlier than there.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 20 |
| 50% (median) | January 17 |
| 10% (safe for tender plants) | February 16 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | November 24 |
| 50% (median) | December 12 |
| 90% (late) | January 14 |
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
Atherton, 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 Redwood City, CA weather station, 4 km away (elevation 30 ft (9 m)).
Frost dates near Atherton
- Palo Alto Feb 1 · Dec 7
- Stanford Feb 1 · Dec 7
- Redwood City Jan 17 · Dec 12
- Menlo Park Feb 25 · Nov 25
- San Carlos Jan 17 · Dec 12
- Portola Valley Mar 21 · Dec 15
- Belmont Jan 17 · Dec 12
- Los Altos Jan 6 · Dec 23
- Mountain View Jan 6 · Dec 23
- San Mateo Dec 29 · Dec 26
Frequently asked questions
When is the last frost in Atherton, CA?
The median last spring frost in Atherton, CA is January 17. There is still about a 10% chance of frost after February 16, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Atherton, CA?
The median first fall frost is December 12, with about a 10% chance of frost before November 24.
How long is the growing season in Atherton, CA?
About 329 days between the median last spring frost and first fall frost.
What planting zone is Atherton, CA?
Atherton, CA is in USDA hardiness zone 9b.