Frost Dates for Rancho Santa Margarita, CA
In Rancho Santa Margarita, CA, the average last spring frost is around Jan 5 and the average first fall frost around Dec 25, for a growing season of about 365 days. For frost-tender plants, wait until Feb 2, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Tustin Irvine Rch, CA weather station, 10 miles away, elevation 235 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 2 | Dec 3 |
| 20% | Jan 23 | Dec 9 |
| 30% | Jan 14 | Dec 13 |
| 40% | Jan 9 | Dec 19 |
| 50% | Jan 5 | Dec 25 |
| 60% | Dec 31 | Dec 30 |
| 70% | Dec 28 | Jan 3 |
| 80% | Dec 22 | Jan 9 |
| 90% | Dec 14 | Jan 20 |
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 1 | Dec 13 |
| Frost / freeze (32°F) | Jan 5 | Dec 25 |
| Hard freeze (28°F) | — | — |
Planting calendar for Rancho Santa Margarita
Transplant Jan 12 – Jan 26
Transplant Jan 19 – Feb 2
Transplant Jan 19 – Feb 2
Transplant Jan 12 – Jan 26
Sow or transplant Jan 12 – Jan 26
Sow or transplant Jan 12 – Jan 26
Sow or transplant Jan 19 – Feb 2
Sow or transplant Dec 8 – Dec 22
Fall sowing Oct 30 – Nov 27
Fall sowing Oct 30 – Nov 20
Fall sowing Oct 16 – Oct 30
Sow or transplant Dec 8 – Dec 22
Fall sowing Oct 16 – Nov 13
Transplant Dec 22 – Jan 5
Fall sowing Oct 2 – Oct 16
Transplant Dec 15 – Dec 29
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 8 – Dec 22
Based on the average last frost (Jan 5) and first frost (Dec 25). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.