Frost Dates for Issaquah, WA
In Issaquah, WA, the average last spring frost is around Mar 13 and the average first fall frost around Nov 16, for a growing season of about 248 days. For frost-tender plants, wait until Mar 31, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Renton Muni Airport, WA weather station, 9 miles away, elevation 29 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 31 | Oct 29 |
| 20% | Mar 25 | Nov 2 |
| 30% | Mar 22 | Nov 7 |
| 40% | Mar 18 | Nov 11 |
| 50% | Mar 13 | Nov 16 |
| 60% | Mar 8 | Nov 20 |
| 70% | Mar 3 | Nov 25 |
| 80% | Feb 27 | Dec 1 |
| 90% | Feb 19 | Dec 9 |
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 6 | Oct 31 |
| Frost / freeze (32°F) | Mar 13 | Nov 16 |
| Hard freeze (28°F) | Feb 13 | Dec 6 |
Planting calendar for Issaquah
Transplant Mar 20 – Apr 3
Transplant Mar 27 – Apr 10
Transplant Mar 27 – Apr 10
Transplant Mar 20 – Apr 3
Sow or transplant Mar 20 – Apr 3
Sow or transplant Mar 20 – Apr 3
Sow or transplant Mar 27 – Apr 10
Sow or transplant Feb 13 – Feb 27
Fall sowing Sep 21 – Oct 19
Fall sowing Sep 21 – Oct 12
Fall sowing Sep 7 – Sep 21
Sow or transplant Feb 13 – Feb 27
Fall sowing Sep 7 – Oct 5
Transplant Feb 27 – Mar 13
Fall sowing Aug 24 – Sep 7
Transplant Feb 20 – Mar 6
Fall sowing Aug 24 – Sep 7
Fall sowing Aug 24 – Sep 7
Fall sowing Oct 5 – Oct 26
Fall sowing Sep 7 – Sep 21
Plant Feb 13 – Feb 27
Based on the average last frost (Mar 13) and first frost (Nov 16). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.