Last spring frost
Mar 29
Frost Dates for Portland, OR
First fall frost
Nov 9
Growing season
223 days
Hardiness zone
9a
In an average year around Portland, OR, the last spring frost (32°F) is about Mar 29 and the first fall frost is about Nov 9, giving roughly a 223-day growing season. To be safe most years, wait until Mar 6 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) | May 10 | Apr 24 | Apr 3 |
| Freeze (32°F) | Apr 18 | Mar 29 | Mar 6 |
| Hard (28°F) | Mar 27 | Mar 3 | Feb 4 |
| Severe (24°F) | Mar 1 | Feb 7 | Dec 26 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 10 | May 3 | Apr 30 | Apr 27 | Apr 24 | Apr 20 | Apr 15 | Apr 11 | Apr 3 |
| 32°F | Apr 18 | Apr 12 | Apr 5 | Apr 2 | Mar 29 | Mar 25 | Mar 20 | Mar 14 | Mar 6 |
| 28°F | Mar 27 | Mar 18 | Mar 12 | Mar 7 | Mar 3 | Feb 27 | Feb 23 | Feb 18 | Feb 4 |
| 24°F | Mar 1 | Feb 24 | Feb 19 | Feb 14 | Feb 7 | Jan 31 | Jan 21 | Jan 9 | Dec 26 |
| 20°F | Feb 21 | Feb 11 | Feb 1 | Jan 25 | Jan 16 | Jan 7 | Dec 30 | Dec 18 | Dec 6 |
| 16°F | Feb 8 | Jan 27 | Jan 17 | Jan 7 | Dec 30 | Dec 25 | Dec 19 | Dec 10 | Dec 3 |
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 7 | Oct 24 | Nov 12 |
| Freeze (32°F) | Oct 22 | Nov 9 | Nov 30 |
| Hard (28°F) | Nov 3 | Nov 26 | Dec 22 |
| Severe (24°F) | Nov 16 | Dec 14 | Jan 24 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 7 | Oct 13 | Oct 17 | Oct 21 | Oct 24 | Oct 28 | Oct 31 | Nov 5 | Nov 12 |
| 32°F | Oct 22 | Oct 29 | Nov 1 | Nov 5 | Nov 9 | Nov 13 | Nov 17 | Nov 23 | Nov 30 |
| 28°F | Nov 3 | Nov 11 | Nov 17 | Nov 22 | Nov 26 | Dec 1 | Dec 6 | Dec 12 | Dec 22 |
| 24°F | Nov 16 | Nov 25 | Dec 1 | Dec 7 | Dec 14 | Dec 22 | Dec 28 | Jan 5 | Jan 24 |
| 20°F | Nov 27 | Dec 3 | Dec 10 | Dec 18 | Dec 25 | Jan 1 | Jan 7 | Jan 21 | Feb 11 |
| 16°F | Dec 1 | Dec 6 | Dec 12 | Dec 19 | Dec 25 | Jan 1 | Jan 6 | Jan 18 | Feb 4 |
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: Vancouver Pearson Ap, Wa, about 4.1 miles away@if(!empty($station['elevation_ft'])), at 30 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 Mar 29. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 6.
When is the first frost in the fall?
The first fall frost around Portland, OR typically arrives about Nov 9. 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 Mar 29 on average, or Mar 6 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 223 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 97203 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026