Jamul, CA frost dates
Frost is light and occasional here — typically a few cold nights around midwinter (about 3 a year). Cover tender plants when frost is forecast.
How Jamul compares
- In a typical year, frost nights in Jamul fall between December 21 and January 6. In 1 year in 10 the first frost comes as early as December 1, or the last frost as late as February 7.
- Jamul shares its weather station with El Cajon, CA, 14 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 13 |
| 50% (median) | January 6 |
| 10% (safe for tender plants) | February 7 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | December 1 |
| 50% (median) | December 21 |
| 90% (late) | January 15 |
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
Jamul, 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 El Cajon, CA weather station, 13 km away (elevation 495 ft (151 m)).
Frost dates near Jamul
- El Cajon Jan 6 · Dec 21
- Alpine Feb 12 · Dec 24
- Dulzura Jan 6 · Dec 31
- Spring Valley Jan 6 · Dec 21
- Lakeside Jan 6 · Dec 21
- La Mesa Jan 6 · Dec 21
- Lemon Grove Jan 6 · Dec 21
- Bonita rare frost
- Santee Jan 6 · Dec 21
- Chula Vista rare frost
Frequently asked questions
When is the last frost in Jamul, CA?
The median last spring frost in Jamul, CA is January 6. 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 Jamul, CA?
The median first fall frost is December 21, with about a 10% chance of frost before December 1.
How long is the growing season in Jamul, CA?
About 349 days between the median last spring frost and first fall frost.
What planting zone is Jamul, CA?
Jamul, CA is in USDA hardiness zone 10a.