Frost Dates for Walnut Creek, CA
In Walnut Creek, CA, the average last spring frost is around Jan 7 and the average first fall frost around Dec 19, for a growing season of about 346 days. For frost-tender plants, wait until Feb 1, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Concord Wwtp, CA weather station, 6 miles away, elevation 40 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 1 | Dec 1 |
| 20% | Jan 25 | Dec 5 |
| 30% | Jan 17 | Dec 11 |
| 40% | Jan 11 | Dec 16 |
| 50% | Jan 7 | Dec 19 |
| 60% | Jan 3 | Dec 23 |
| 70% | Dec 31 | Dec 29 |
| 80% | Dec 26 | Jan 3 |
| 90% | Dec 19 | Jan 12 |
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 9 | Dec 2 |
| Frost / freeze (32°F) | Jan 7 | Dec 19 |
| Hard freeze (28°F) | Dec 31 | Dec 29 |
Planting calendar for Walnut Creek
Transplant Jan 14 – Jan 28
Transplant Jan 21 – Feb 4
Transplant Jan 21 – Feb 4
Transplant Jan 14 – Jan 28
Sow or transplant Jan 14 – Jan 28
Sow or transplant Jan 14 – Jan 28
Sow or transplant Jan 21 – Feb 4
Sow or transplant Dec 10 – Dec 24
Fall sowing Oct 24 – Nov 21
Fall sowing Oct 24 – Nov 14
Fall sowing Oct 10 – Oct 24
Sow or transplant Dec 10 – Dec 24
Fall sowing Oct 10 – Nov 7
Transplant Dec 24 – Jan 7
Fall sowing Sep 26 – Oct 10
Transplant Dec 17 – Dec 31
Fall sowing Sep 26 – Oct 10
Fall sowing Sep 26 – Oct 10
Fall sowing Nov 7 – Nov 28
Fall sowing Oct 10 – Oct 24
Plant Dec 10 – Dec 24
Based on the average last frost (Jan 7) and first frost (Dec 19). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.