Frost Dates for Bothell, WA
In Bothell, WA, the average last spring frost is around Mar 8 and the average first fall frost around Nov 23, for a growing season of about 259 days. For frost-tender plants, wait until Mar 29, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Seattle Sand Pt Wsfo, WA weather station, 6 miles away, elevation 60 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 29 | Nov 4 |
| 20% | Mar 21 | Nov 10 |
| 30% | Mar 16 | Nov 15 |
| 40% | Mar 11 | Nov 19 |
| 50% | Mar 8 | Nov 23 |
| 60% | Mar 3 | Nov 27 |
| 70% | Feb 27 | Dec 1 |
| 80% | Feb 23 | Dec 6 |
| 90% | Feb 13 | Dec 16 |
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 4 | Nov 5 |
| Frost / freeze (32°F) | Mar 8 | Nov 23 |
| Hard freeze (28°F) | Feb 11 | Dec 11 |
Planting calendar for Bothell
Transplant Mar 15 – Mar 29
Transplant Mar 22 – Apr 5
Transplant Mar 22 – Apr 5
Transplant Mar 15 – Mar 29
Sow or transplant Mar 15 – Mar 29
Sow or transplant Mar 15 – Mar 29
Sow or transplant Mar 22 – Apr 5
Sow or transplant Feb 8 – Feb 22
Fall sowing Sep 28 – Oct 26
Fall sowing Sep 28 – Oct 19
Fall sowing Sep 14 – Sep 28
Sow or transplant Feb 8 – Feb 22
Fall sowing Sep 14 – Oct 12
Transplant Feb 22 – Mar 8
Fall sowing Aug 31 – Sep 14
Transplant Feb 15 – Mar 1
Fall sowing Aug 31 – Sep 14
Fall sowing Aug 31 – Sep 14
Fall sowing Oct 12 – Nov 2
Fall sowing Sep 14 – Sep 28
Plant Feb 8 – Feb 22
Based on the average last frost (Mar 8) and first frost (Nov 23). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.