Frost Dates for Lewiston, ID
In Lewiston, ID, the average last spring frost is around Apr 6 and the average first fall frost around Oct 26, for a growing season of about 200 days. For frost-tender plants, wait until Apr 26, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Lewiston Nez Perce Co Airport, ID weather station, 2 miles away, elevation 1,436 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 26 | Oct 10 |
| 20% | Apr 19 | Oct 14 |
| 30% | Apr 14 | Oct 18 |
| 40% | Apr 10 | Oct 23 |
| 50% | Apr 6 | Oct 26 |
| 60% | Apr 3 | Oct 29 |
| 70% | Mar 31 | Nov 1 |
| 80% | Mar 27 | Nov 5 |
| 90% | Mar 20 | Nov 12 |
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 29 | Oct 13 |
| Frost / freeze (32°F) | Apr 6 | Oct 26 |
| Hard freeze (28°F) | Mar 15 | Nov 8 |
Planting calendar for Lewiston
Transplant Apr 13 – Apr 27
Transplant Apr 20 – May 4
Transplant Apr 20 – May 4
Transplant Apr 13 – Apr 27
Sow or transplant Apr 13 – Apr 27
Sow or transplant Apr 13 – Apr 27
Sow or transplant Apr 20 – May 4
Sow or transplant Mar 9 – Mar 23
Fall sowing Aug 31 – Sep 28
Fall sowing Aug 31 – Sep 21
Fall sowing Aug 17 – Aug 31
Sow or transplant Mar 9 – Mar 23
Fall sowing Aug 17 – Sep 14
Transplant Mar 23 – Apr 6
Fall sowing Aug 3 – Aug 17
Transplant Mar 16 – Mar 30
Fall sowing Aug 3 – Aug 17
Fall sowing Aug 3 – Aug 17
Fall sowing Sep 14 – Oct 5
Fall sowing Aug 17 – Aug 31
Plant Mar 9 – Mar 23
Based on the average last frost (Apr 6) and first frost (Oct 26). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.