Frost Dates for Sammamish, WA
In Sammamish, WA, the average last spring frost is around Mar 30 and the average first fall frost around Nov 7, for a growing season of about 223 days. For frost-tender plants, wait until Apr 21, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Snoqualmie Falls, WA weather station, 10 miles away, elevation 440 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 21 | Oct 22 |
| 20% | Apr 13 | Oct 28 |
| 30% | Apr 8 | Nov 1 |
| 40% | Apr 3 | Nov 3 |
| 50% | Mar 30 | Nov 7 |
| 60% | Mar 25 | Nov 11 |
| 70% | Mar 20 | Nov 17 |
| 80% | Mar 13 | Nov 24 |
| 90% | Mar 4 | Dec 1 |
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 26 | Oct 22 |
| Frost / freeze (32°F) | Mar 30 | Nov 7 |
| Hard freeze (28°F) | Feb 27 | Nov 29 |
Planting calendar for Sammamish
Transplant Apr 6 – Apr 20
Transplant Apr 13 – Apr 27
Transplant Apr 13 – Apr 27
Transplant Apr 6 – Apr 20
Sow or transplant Apr 6 – Apr 20
Sow or transplant Apr 6 – Apr 20
Sow or transplant Apr 13 – Apr 27
Sow or transplant Mar 2 – Mar 16
Fall sowing Sep 12 – Oct 10
Fall sowing Sep 12 – Oct 3
Fall sowing Aug 29 – Sep 12
Sow or transplant Mar 2 – Mar 16
Fall sowing Aug 29 – Sep 26
Transplant Mar 16 – Mar 30
Fall sowing Aug 15 – Aug 29
Transplant Mar 9 – Mar 23
Fall sowing Aug 15 – Aug 29
Fall sowing Aug 15 – Aug 29
Fall sowing Sep 26 – Oct 17
Fall sowing Aug 29 – Sep 12
Plant Mar 2 – Mar 16
Based on the average last frost (Mar 30) and first frost (Nov 7). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.