Frost dates for 93099 — Simi Valley, CA
Frost is light and occasional here — typically a few cold nights around midwinter (about 11 a year). Cover tender plants when frost is forecast.
How Simi Valley compares
- In a typical year, frost nights in Simi Valley fall between December 15 and January 24. In 1 year in 10 the first frost comes as early as November 27, or the last frost as late as March 5.
- Compared with Thousand Oaks, CA, 10 km away, the last frost here is 24 days later than there.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 21 |
| 50% (median) | January 24 |
| 10% (safe for tender plants) | March 5 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | November 27 |
| 50% (median) | December 15 |
| 90% (late) | January 26 |
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
Simi 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 Woodland Hills Pierce College, CA weather station, 21 km away (elevation 791 ft (241 m)).
ZIP codes in Simi Valley: 93062 93063 93065 93094 93099
Frost dates near Simi Valley
- Brandeis Jan 24 · Dec 15
- Moorpark Dec 31 · Dec 28
- Oak Park Jan 24 · Dec 15
- Thousand Oaks Dec 31 · Dec 28
- Westlake Village Jan 24 · Dec 15
- West Hills Jan 24 · Dec 15
- Agoura Hills Jan 24 · Dec 15
- Newbury Park Dec 31 · Dec 28
Frequently asked questions
When is the last frost in Simi Valley, CA?
The median last spring frost in Simi Valley, CA is January 24. There is still about a 10% chance of frost after March 5, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Simi Valley, CA?
The median first fall frost is December 15, with about a 10% chance of frost before November 27.
How long is the growing season in Simi Valley, CA?
About 325 days between the median last spring frost and first fall frost.
What planting zone is Simi Valley, CA?
Simi Valley, CA is in USDA hardiness zone 10a.