Frost Dates for Kennewick, WA
In Kennewick, WA, the average last spring frost is around Mar 28 and the average first fall frost around Oct 30, for a growing season of about 216 days. For frost-tender plants, wait until Apr 10, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Kennewick, WA weather station, 4 miles away, elevation 390 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 10 | Oct 18 |
| 20% | Apr 5 | Oct 22 |
| 30% | Apr 2 | Oct 25 |
| 40% | Mar 31 | Oct 28 |
| 50% | Mar 28 | Oct 30 |
| 60% | Mar 25 | Nov 2 |
| 70% | Mar 21 | Nov 5 |
| 80% | Mar 15 | Nov 10 |
| 90% | Mar 9 | Nov 15 |
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 14 | Oct 21 |
| Frost / freeze (32°F) | Mar 28 | Oct 30 |
| Hard freeze (28°F) | Mar 8 | Nov 11 |
Planting calendar for Kennewick
Transplant Apr 4 – Apr 18
Transplant Apr 11 – Apr 25
Transplant Apr 11 – Apr 25
Transplant Apr 4 – Apr 18
Sow or transplant Apr 4 – Apr 18
Sow or transplant Apr 4 – Apr 18
Sow or transplant Apr 11 – Apr 25
Sow or transplant Feb 28 – Mar 14
Fall sowing Sep 4 – Oct 2
Fall sowing Sep 4 – Sep 25
Fall sowing Aug 21 – Sep 4
Sow or transplant Feb 28 – Mar 14
Fall sowing Aug 21 – Sep 18
Transplant Mar 14 – Mar 28
Fall sowing Aug 7 – Aug 21
Transplant Mar 7 – Mar 21
Fall sowing Aug 7 – Aug 21
Fall sowing Aug 7 – Aug 21
Fall sowing Sep 18 – Oct 9
Fall sowing Aug 21 – Sep 4
Plant Feb 28 – Mar 14
Based on the average last frost (Mar 28) and first frost (Oct 30). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.