Last spring frost
Feb 25
Frost Dates for Portland, OR
First fall frost
Dec 1
Growing season
280 days
Hardiness zone
9a
In an average year around Portland, OR, the last spring frost (32°F) is about Feb 25 and the first fall frost is about Dec 1, giving roughly a 280-day growing season. To be safe most years, wait until Jan 24 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Apr 21 | Mar 29 | Mar 7 |
| Freeze (32°F) | Mar 21 | Feb 25 | Jan 24 |
| Hard (28°F) | Feb 26 | Jan 31 | Dec 21 |
| Severe (24°F) | Feb 18 | Jan 15 | Dec 8 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 21 | Apr 13 | Apr 5 | Apr 1 | Mar 29 | Mar 25 | Mar 20 | Mar 14 | Mar 7 |
| 32°F | Mar 21 | Mar 13 | Mar 6 | Feb 28 | Feb 25 | Feb 18 | Feb 11 | Feb 3 | Jan 24 |
| 28°F | Feb 26 | Feb 18 | Feb 10 | Feb 4 | Jan 31 | Jan 23 | Jan 14 | Jan 3 | Dec 21 |
| 24°F | Feb 18 | Feb 9 | Feb 1 | Jan 26 | Jan 15 | Jan 6 | Dec 29 | Dec 20 | Dec 8 |
| 20°F | Feb 18 | Feb 5 | Feb 1 | Jan 25 | Jan 13 | Jan 1 | Dec 24 | Dec 19 | Dec 7 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Oct 28 | Nov 12 | Dec 1 |
| Freeze (32°F) | Nov 10 | Dec 1 | Dec 27 |
| Hard (28°F) | Nov 25 | Dec 20 | Jan 30 |
| Severe (24°F) | Nov 30 | Dec 29 | Feb 11 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 28 | Nov 2 | Nov 6 | Nov 10 | Nov 12 | Nov 16 | Nov 21 | Nov 25 | Dec 1 |
| 32°F | Nov 10 | Nov 16 | Nov 22 | Nov 26 | Dec 1 | Dec 5 | Dec 11 | Dec 18 | Dec 27 |
| 28°F | Nov 25 | Dec 2 | Dec 7 | Dec 13 | Dec 20 | Dec 27 | Jan 3 | Jan 13 | Jan 30 |
| 24°F | Nov 30 | Dec 7 | Dec 15 | Dec 22 | Dec 29 | Jan 6 | Jan 16 | Jan 30 | Feb 11 |
| 20°F | Dec 6 | Dec 14 | Dec 21 | Dec 28 | Jan 6 | Jan 16 | Jan 29 | Feb 3 | Feb 14 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Portland Kgw-Tv, Or, about 0.9 miles away@if(!empty($station['elevation_ft'])), at 159 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Portland, OR?
On average, the last spring frost (32°F) around Portland, OR is about Feb 25. In cooler years it can run later, so for a safer bet many gardeners wait until Jan 24.
When is the first frost in the fall?
The first fall frost around Portland, OR typically arrives about Dec 1. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Feb 25 on average, or Jan 24 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 280 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 97208 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026