Frost Dates for Napa, CA
In Napa, CA, the average last spring frost is around Feb 12 and the average first fall frost around Dec 4, for a growing season of about 299 days. For frost-tender plants, wait until Mar 13, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Napa State Hospital, CA weather station, 2 miles away, elevation 35 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 13 | Nov 15 |
| 20% | Mar 3 | Nov 23 |
| 30% | Feb 27 | Nov 28 |
| 40% | Feb 20 | Dec 1 |
| 50% | Feb 12 | Dec 4 |
| 60% | Feb 5 | Dec 7 |
| 70% | Jan 29 | Dec 13 |
| 80% | Jan 18 | Dec 20 |
| 90% | Jan 3 | Jan 4 |
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 27 | Nov 17 |
| Frost / freeze (32°F) | Feb 12 | Dec 4 |
| Hard freeze (28°F) | Jan 11 | Dec 19 |
Planting calendar for Napa
Transplant Feb 19 – Mar 5
Transplant Feb 26 – Mar 12
Transplant Feb 26 – Mar 12
Transplant Feb 19 – Mar 5
Sow or transplant Feb 19 – Mar 5
Sow or transplant Feb 19 – Mar 5
Sow or transplant Feb 26 – Mar 12
Sow or transplant Jan 15 – Jan 29
Fall sowing Oct 9 – Nov 6
Fall sowing Oct 9 – Oct 30
Fall sowing Sep 25 – Oct 9
Sow or transplant Jan 15 – Jan 29
Fall sowing Sep 25 – Oct 23
Transplant Jan 29 – Feb 12
Fall sowing Sep 11 – Sep 25
Transplant Jan 22 – Feb 5
Fall sowing Sep 11 – Sep 25
Fall sowing Sep 11 – Sep 25
Fall sowing Oct 23 – Nov 13
Fall sowing Sep 25 – Oct 9
Plant Jan 15 – Jan 29
Based on the average last frost (Feb 12) and first frost (Dec 4). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.