Frost dates for 92331 — Fontana, CA
Frost is light and occasional here — typically a few cold nights around midwinter (about 2 a year). Cover tender plants when frost is forecast.
How Fontana compares
- In a typical year, frost nights in Fontana fall between December 30 and January 4. In 1 year in 10 the first frost comes as early as December 11, or the last frost as late as February 7.
- Compared with San Bernardino, CA, 15 km away, the last frost here is 23 days earlier than there.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 14 |
| 50% (median) | January 4 |
| 10% (safe for tender plants) | February 7 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | December 11 |
| 50% (median) | December 30 |
| 90% (late) | February 1 |
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
Fontana, 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 Ontario Intl Ap, CA weather station, 13 km away (elevation 948 ft (289 m)).
ZIP codes in Fontana: 92331 92334 92335 92336 92337
Frost dates near Fontana
- Bloomington Jan 10 · Jan 2
- Rialto Jan 10 · Jan 2
- Rancho Cucamonga Jan 4 · Dec 30
- Guasti Jan 4 · Dec 30
- Mira Loma Jan 9 · Dec 30
- Grand Terrace Jan 10 · Jan 2
- San Bernardino Jan 27 · Dec 19
- March Air Reserve Base Jan 9 · Dec 25
Frequently asked questions
When is the last frost in Fontana, CA?
The median last spring frost in Fontana, CA is January 4. There is still about a 10% chance of frost after February 7, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Fontana, CA?
The median first fall frost is December 30, with about a 10% chance of frost before December 11.
How long is the growing season in Fontana, CA?
About 360 days between the median last spring frost and first fall frost.
What planting zone is Fontana, CA?
Fontana, CA is in USDA hardiness zone 10a.