Frost dates for 91016 — Monrovia, 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 Monrovia compares
- In a typical year, frost nights in Monrovia fall between January 2 and January 4. In 1 year in 10 the first frost comes as early as December 18, or the last frost as late as January 28.
- Monrovia shares its weather station with Arcadia, CA, 3 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | December 19 |
| 50% (median) | January 4 |
| 10% (safe for tender plants) | January 28 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | December 18 |
| 50% (median) | January 2 |
| 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
Monrovia, 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 San Gabriel Fire Dept, CA weather station, 11 km away (elevation 364 ft (111 m)).
ZIP codes in Monrovia: 91016 91017
Frost dates near Monrovia
- Duarte Apr 28 · Nov 15
- Arcadia Jan 4 · Jan 2
- Sierra Madre Apr 28 · Nov 15
- Baldwin Park Jan 4 · Jan 2
- Temple City Jan 4 · Jan 2
- El Monte Jan 4 · Jan 2
- Azusa Jan 8 · Dec 28
- San Gabriel Jan 4 · Jan 2
Frequently asked questions
When is the last frost in Monrovia, CA?
The median last spring frost in Monrovia, CA is January 4. There is still about a 10% chance of frost after January 28, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Monrovia, CA?
The median first fall frost is January 2, with about a 10% chance of frost before December 18.
How long is the growing season in Monrovia, CA?
About 363 days between the median last spring frost and first fall frost.
What planting zone is Monrovia, CA?
Monrovia, CA is in USDA hardiness zone 10a.