Frost Dates for Riverside, CA
In Riverside, CA, the average last spring frost is around Jan 9 and the average first fall frost around Dec 25, for a growing season of about 353 days. For frost-tender plants, wait until Feb 25, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Riverside Fire Stn 3, CA weather station, under 1 mile away, elevation 840 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | Feb 25 | Dec 1 |
| 20% | Feb 6 | Dec 10 |
| 30% | Jan 25 | Dec 15 |
| 40% | Jan 17 | Dec 20 |
| 50% | Jan 9 | Dec 25 |
| 60% | Jan 4 | Dec 30 |
| 70% | Dec 31 | Jan 4 |
| 80% | Dec 25 | Jan 11 |
| 90% | Dec 16 | Jan 27 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | Feb 19 | Dec 6 |
| Frost / freeze (32°F) | Jan 9 | Dec 25 |
| Hard freeze (28°F) | Dec 31 | Dec 29 |
Planting calendar for Riverside
Transplant Jan 16 – Jan 30
Transplant Jan 23 – Feb 6
Transplant Jan 23 – Feb 6
Transplant Jan 16 – Jan 30
Sow or transplant Jan 16 – Jan 30
Sow or transplant Jan 16 – Jan 30
Sow or transplant Jan 23 – Feb 6
Sow or transplant Dec 12 – Dec 26
Fall sowing Oct 30 – Nov 27
Fall sowing Oct 30 – Nov 20
Fall sowing Oct 16 – Oct 30
Sow or transplant Dec 12 – Dec 26
Fall sowing Oct 16 – Nov 13
Transplant Dec 26 – Jan 9
Fall sowing Oct 2 – Oct 16
Transplant Dec 19 – Jan 2
Fall sowing Oct 2 – Oct 16
Fall sowing Oct 2 – Oct 16
Fall sowing Nov 13 – Dec 4
Fall sowing Oct 16 – Oct 30
Plant Dec 12 – Dec 26
Based on the average last frost (Jan 9) and first frost (Dec 25). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.