Frost Dates for Simi Valley, CA
In Simi Valley, CA, the average last spring frost is around Jan 24 and the average first fall frost around Dec 15, for a growing season of about 329 days. For frost-tender plants, wait until Mar 5, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Woodland Hills Pierce College, CA weather station, 12 miles away, elevation 790 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% | Mar 5 | Nov 27 |
| 20% | Feb 23 | Dec 2 |
| 30% | Feb 12 | Dec 6 |
| 40% | Feb 3 | Dec 11 |
| 50% | Jan 24 | Dec 15 |
| 60% | Jan 15 | Dec 22 |
| 70% | Jan 6 | Dec 28 |
| 80% | Dec 31 | Jan 4 |
| 90% | Dec 21 | Jan 26 |
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) | Mar 2 | Nov 29 |
| Frost / freeze (32°F) | Jan 24 | Dec 15 |
| Hard freeze (28°F) | Dec 31 | Dec 26 |
Planting calendar for Simi Valley
Transplant Jan 31 – Feb 14
Transplant Feb 7 – Feb 21
Transplant Feb 7 – Feb 21
Transplant Jan 31 – Feb 14
Sow or transplant Jan 31 – Feb 14
Sow or transplant Jan 31 – Feb 14
Sow or transplant Feb 7 – Feb 21
Sow or transplant Dec 27 – Jan 10
Fall sowing Oct 20 – Nov 17
Fall sowing Oct 20 – Nov 10
Fall sowing Oct 6 – Oct 20
Sow or transplant Dec 27 – Jan 10
Fall sowing Oct 6 – Nov 3
Transplant Jan 10 – Jan 24
Fall sowing Sep 22 – Oct 6
Transplant Jan 3 – Jan 17
Fall sowing Sep 22 – Oct 6
Fall sowing Sep 22 – Oct 6
Fall sowing Nov 3 – Nov 24
Fall sowing Oct 6 – Oct 20
Plant Dec 27 – Jan 10
Based on the average last frost (Jan 24) and first frost (Dec 15). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.