Frost dates for 91016Monrovia, CA
Frost occurs in about 15% of years near Monrovia, based on NOAA 1991-2020 records for the San Gabriel Fire Dept, CA station.
Frost occurs in about 15% of years. Frost-tender plants can usually grow year-round, but cover them if a rare cold snap is forecast.
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Dec 20 · Jan 17 · Feb 20 | Dec 6 · Dec 26 · Jan 30 | 346 days | 75% |
| Frost / freeze (32°F) | Dec 19 · Jan 4 · Jan 28 | Dec 18 · Jan 2 · Jan 26 | 365 days | 15% |
| Hard freeze (28°F) | — | — | 365 days | 0% |
Where these dates come from
ZIP code 91016 is matched to the NOAA station San Gabriel Fire Dept, CA, 11.3 km away, at 363 ft elevation (165 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| San Gabriel Fire Dept, CA (used) | 363 ft | Jan 4 | Jan 2 |
| Mt Wilson Cbs, CA | 5,710 ft | Apr 28 | Nov 15 |
| Pasadena, CA | 864 ft | Jan 8 | Jan 7 |
| Pomona/Fairplex, CA | 999 ft | Jan 8 | Dec 28 |
Frost dates near Monrovia
- Monrovia, CA 91017 · last Jan 4, first Jan 2
- Duarte, CA 91009 · last Jan 4, first Jan 2
- Arcadia, CA 91006 · last Jan 4, first Jan 2
- Sierra Madre, CA 91025 · last Jan 8, first Jan 7
- Baldwin Park, CA 91706 · last Jan 4, first Jan 2
- Temple City, CA 91780 · last Jan 4, first Jan 2
- El Monte, CA 91731 · last Jan 4, first Jan 2
- Pasadena, CA 91107 · last Jan 8, first Jan 7
Frequently asked questions
- When is the last frost in Monrovia, CA?
- Frost occurs in about 15% of years at the nearest NOAA station (San Gabriel Fire Dept, CA), so there is no reliable average last frost date.
- When is the first frost in Monrovia, CA?
- Frost occurs in about 15% of years at the nearest NOAA station.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.