Frost dates for Ontario, California
In a typical year, Ontario’s last spring frost lands around Jan 4 and the first fall frost around Dec 30, a growing season of about 360 days. These are odds drawn from 30-year NOAA climate normals, not a promise. USDA zone 10a.
| Odds | Last spring frost | First fall frost |
|---|---|---|
| 10 percent | Dec 14 | Dec 11 |
| 50 percent | Jan 4 | Dec 30 |
| 90 percent | Feb 7 | Feb 1 |
A 10 percent year is an early year, a 90 percent year a late one. Frost-sensitive planting usually waits for the 90 percent side of the last-frost band.
Soil in Ontario is typically around 78°F at 4 inches this time of year, estimated from the last two weeks of normal air temperatures.
Plantable now in Ontario
- Eggplant (Black Beauty)
- Sweet pepper (California Wonder)
- Tomato (Big Beef)
- Bush bean (Blue Lake Bush 274)
- Pole bean (Blue Lake Pole)
- Hot pepper (Jalapeño)
- Zucchini (Black Beauty)
- Zinnia (Benary's Giant)
Timing comes from the same temperature engine the app uses, run against Ontario’s normals for today.
Nearby cities
- Pomona, CA (around Jan 8 to Dec 28)
- Rancho Cucamonga, CA (around Jan 4 to Dec 30)
- Fontana, CA (around Jan 9 to Dec 30)
- Corona, CA (around Jan 17 to Dec 19)
- Riverside, CA (around Jan 9 to Dec 25)
Row & Bed is a plant reference built around your garden: your zone, your frost dates, your forecast, and a cited page for every variety in your beds.
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