Frost Dates for Mount Vernon, WA
In Mount Vernon, WA, the average last spring frost is around Mar 24 and the average first fall frost around Nov 3, for a growing season of about 224 days. For frost-tender plants, wait until Apr 14, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Mt Vernon 3 Wnw, WA weather station, 4 miles away, elevation 14 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% | Apr 14 | Oct 12 |
| 20% | Apr 7 | Oct 21 |
| 30% | Apr 1 | Oct 26 |
| 40% | Mar 28 | Oct 31 |
| 50% | Mar 24 | Nov 3 |
| 60% | Mar 20 | Nov 8 |
| 70% | Mar 15 | Nov 13 |
| 80% | Mar 10 | Nov 19 |
| 90% | Mar 3 | Nov 25 |
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) | Apr 18 | Oct 16 |
| Frost / freeze (32°F) | Mar 24 | Nov 3 |
| Hard freeze (28°F) | Feb 27 | Nov 25 |
Planting calendar for Mount Vernon
Transplant Mar 31 – Apr 14
Transplant Apr 7 – Apr 21
Transplant Apr 7 – Apr 21
Transplant Mar 31 – Apr 14
Sow or transplant Mar 31 – Apr 14
Sow or transplant Mar 31 – Apr 14
Sow or transplant Apr 7 – Apr 21
Sow or transplant Feb 24 – Mar 10
Fall sowing Sep 8 – Oct 6
Fall sowing Sep 8 – Sep 29
Fall sowing Aug 25 – Sep 8
Sow or transplant Feb 24 – Mar 10
Fall sowing Aug 25 – Sep 22
Transplant Mar 10 – Mar 24
Fall sowing Aug 11 – Aug 25
Transplant Mar 3 – Mar 17
Fall sowing Aug 11 – Aug 25
Fall sowing Aug 11 – Aug 25
Fall sowing Sep 22 – Oct 13
Fall sowing Aug 25 – Sep 8
Plant Feb 24 – Mar 10
Based on the average last frost (Mar 24) and first frost (Nov 3). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.