Frost dates for 94942 — Mill Valley, CA
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 Mill Valley compares
- In a typical year, frost nights in Mill Valley fall between December 18 and January 16. In 1 year in 10 the first frost comes as early as November 30, or the last frost as late as February 25.
- Compared with San Rafael, CA, 11 km away, the last frost here is 5 days later than there.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 21 |
| 50% (median) | January 16 |
| 10% (safe for tender plants) | February 25 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | November 30 |
| 50% (median) | December 18 |
| 90% (late) | January 19 |
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
Mill Valley, 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 Kentfield, CA weather station, 6 km away (elevation 144 ft (44 m)).
ZIP codes in Mill Valley: 94941 94942
Frost dates near Mill Valley
- Corte Madera Jan 16 · Dec 18
- Larkspur Jan 16 · Dec 18
- Greenbrae Jan 16 · Dec 18
- Kentfield Jan 16 · Dec 18
- Ross Jan 16 · Dec 18
- San Quentin Jan 16 · Dec 18
- Sausalito rare frost
- Belvedere Tiburon Jan 4 · Jan 2
Frequently asked questions
When is the last frost in Mill Valley, CA?
The median last spring frost in Mill Valley, CA is January 16. There is still about a 10% chance of frost after February 25, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Mill Valley, CA?
The median first fall frost is December 18, with about a 10% chance of frost before November 30.
How long is the growing season in Mill Valley, CA?
About 336 days between the median last spring frost and first fall frost.
What planting zone is Mill Valley, CA?
Mill Valley, CA is in USDA hardiness zone 10a.