Frost dates for 91785 — Upland, 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 Upland compares
- In a typical year, frost nights in Upland 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.
- Upland shares its weather station with Ontario, CA, 7 km away, so the two have the same frost dates.
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
Upland, 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, 8 km away (elevation 948 ft (289 m)).
ZIP codes in Upland: 91784 91785 91786
Frost dates near Upland
- Claremont Jan 8 · Dec 28
- Montclair Jan 8 · Dec 28
- Ontario Jan 4 · Dec 30
- Rancho Cucamonga Jan 4 · Dec 30
- Guasti Jan 4 · Dec 30
- La Verne Jan 8 · Dec 28
- Pomona Jan 8 · Dec 28
- Mount Baldy May 16 · Oct 13
Frequently asked questions
When is the last frost in Upland, CA?
The median last spring frost in Upland, 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 Upland, 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 Upland, CA?
About 360 days between the median last spring frost and first fall frost.
What planting zone is Upland, CA?
Upland, CA is in USDA hardiness zone 10a.