Frost Dates for Portland, OR
In Portland, OR, the average last spring frost is around Feb 25 and the average first fall frost around Dec 1, for a growing season of about 280 days. For frost-tender plants, wait until Mar 21, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Portland Kgw-Tv, OR weather station, 2 miles away, elevation 159 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 21 | Nov 10 |
| 20% | Mar 13 | Nov 16 |
| 30% | Mar 6 | Nov 22 |
| 40% | Feb 28 | Nov 26 |
| 50% | Feb 25 | Dec 1 |
| 60% | Feb 18 | Dec 5 |
| 70% | Feb 11 | Dec 11 |
| 80% | Feb 3 | Dec 18 |
| 90% | Jan 24 | Dec 27 |
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) | Mar 29 | Nov 12 |
| Frost / freeze (32°F) | Feb 25 | Dec 1 |
| Hard freeze (28°F) | Jan 31 | Dec 20 |
Planting calendar for Portland
Transplant Mar 4 – Mar 18
Transplant Mar 11 – Mar 25
Transplant Mar 11 – Mar 25
Transplant Mar 4 – Mar 18
Sow or transplant Mar 4 – Mar 18
Sow or transplant Mar 4 – Mar 18
Sow or transplant Mar 11 – Mar 25
Sow or transplant Jan 28 – Feb 11
Fall sowing Oct 6 – Nov 3
Fall sowing Oct 6 – Oct 27
Fall sowing Sep 22 – Oct 6
Sow or transplant Jan 28 – Feb 11
Fall sowing Sep 22 – Oct 20
Transplant Feb 11 – Feb 25
Fall sowing Sep 8 – Sep 22
Transplant Feb 4 – Feb 18
Fall sowing Sep 8 – Sep 22
Fall sowing Sep 8 – Sep 22
Fall sowing Oct 20 – Nov 10
Fall sowing Sep 22 – Oct 6
Plant Jan 28 – Feb 11
Based on the average last frost (Feb 25) and first frost (Dec 1). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.