Frost dates for 91031 — South Pasadena, CA
Frost is light and occasional here — typically a few cold nights around midwinter (about 0 a year). Cover tender plants when frost is forecast.
How South Pasadena compares
- In a typical year, frost nights in South Pasadena fall between January 7 and January 8. In 1 year in 10 the first frost comes as early as December 20, or the last frost as late as February 17.
- Compared with Alhambra, CA, 3 km away, the last frost here is 4 days later than there.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 20 |
| 50% (median) | January 8 |
| 10% (safe for tender plants) | February 17 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | December 20 |
| 50% (median) | January 7 |
| 90% (late) | February 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
South Pasadena, 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 Pasadena, CA weather station, 4 km away (elevation 863 ft (263 m)).
ZIP codes in South Pasadena: 91030 91031
Frost dates near South Pasadena
- Alhambra Jan 4 · Jan 2
- Pasadena Jan 8 · Jan 7
- San Marino Jan 4 · Jan 2
- San Gabriel Jan 4 · Jan 2
- Monterey Park Jan 4 · Jan 2
- Rosemead Jan 4 · Jan 2
- Altadena Jan 8 · Jan 7
- Temple City Jan 4 · Jan 2
Frequently asked questions
When is the last frost in South Pasadena, CA?
The median last spring frost in South Pasadena, CA is January 8. There is still about a 10% chance of frost after February 17, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in South Pasadena, CA?
The median first fall frost is January 7, with about a 10% chance of frost before December 20.
How long is the growing season in South Pasadena, CA?
About 364 days between the median last spring frost and first fall frost.
What planting zone is South Pasadena, CA?
South Pasadena, CA is in USDA hardiness zone 10a.