Frost dates for 91310 — Castaic, CA
Frost is light and occasional here — typically a few cold nights around midwinter (about 1 a year). Cover tender plants when frost is forecast.
How Castaic compares
- In a typical year, frost nights in Castaic fall between January 1 and January 8. In 1 year in 10 the first frost comes as early as November 30, or the last frost as late as March 10.
- Castaic shares its weather station with Valencia, CA, 8 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 8 |
| 50% (median) | January 8 |
| 10% (safe for tender plants) | March 10 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | November 30 |
| 50% (median) | January 1 |
| 90% (late) | February 25 |
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
Castaic, 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 Newhall 5nw, CA weather station, 11 km away (elevation 1,765 ft (538 m)).
ZIP codes in Castaic: 91310 91384
Frost dates near Castaic
- Valencia Jan 8 · Jan 1
- Santa Clarita Jan 8 · Jan 1
- Stevenson Ranch Jan 8 · Jan 1
- Newhall Jan 8 · Jan 1
- Piru Jan 8 · Jan 1
- Canyon Country Jan 8 · Jan 1
- Lake Hughes Apr 6 · Nov 29
- Porter Ranch Jan 2 · Jan 1
Frequently asked questions
When is the last frost in Castaic, CA?
The median last spring frost in Castaic, CA is January 8. There is still about a 10% chance of frost after March 10, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Castaic, CA?
The median first fall frost is January 1, with about a 10% chance of frost before November 30.
How long is the growing season in Castaic, CA?
About 358 days between the median last spring frost and first fall frost.
What planting zone is Castaic, CA?
Castaic, CA is in USDA hardiness zone 10a.