Last frost date in Monrovia, California
April 28
Average last frost in spring. In an early year (1 in 10) it's over by March 31; in a late year (1 in 10) it comes after May 27.
November 15
Average first frost in fall. 1 year in 10 it comes by October 18.
Source: NOAA U.S. Climate Normals 1991–2020, station Mt Wilson Cbs (USC00046006), 6.8 miles from Monrovia, elevation 5,710 ft. NOAA National Centers for Environmental Information. These are long-term averages, not a forecast.
This station is also the nearest one for Duarte and Sierra Madre, so their frost dates are the same as Monrovia's.
| Early year | Average | Late year | |
|---|---|---|---|
| Last frost in spring | Mar 31 | Apr 28 | May 27 |
| First frost in fall | Oct 18 | Nov 15 | Dec 9 |
Frost-free days in an average year: 199
| Chance in a year | Average last in spring | Average first in fall | |
|---|---|---|---|
| Light frost (36°F) | Every year | May 15 | Oct 30 |
| Frost (32°F) | Every year | Apr 28 | Nov 15 |
| Hard freeze (28°F) | Every year | Apr 8 | Dec 4 |
Nights at 32°F or colder in an average year: 50
What to plant now in Monrovia
- Mustard greensAug 15 – Nov 1Now
- Garden peasSept 1 – Nov 1Now
- ParsleySept 1 – Nov 15Now
- RadishesSept 1 – Nov 15Now
- SpinachSept 15 – Nov 1Now
- Corn saladOct 1 – Dec 1Now
- Onion setsOct 1 – Dec 1Now
- Upland cressOct 1 – Dec 1Now
- Asparagus plantsDec 1 – Jan 1Soon
- Spring planting calendar for an average last frost around April 30 Monrovia: April 28
- Fall planting calendar for an average first frost around November 10 Monrovia: November 15
Planting dates: USDA Home and Garden Bulletin No. 9 (1967), “Suburban and Farm Vegetable Gardens,” tables 4 and 5. How we match the table.