Last spring frost
Apr 12
Frost Dates for Cascadia, OR
First fall frost
Oct 28
Growing season
197 days
Hardiness zone
8b
In an average year around Cascadia, OR, the last spring frost (32°F) is about Apr 12 and the first fall frost is about Oct 28, giving roughly a 197-day growing season. To be safe most years, wait until Mar 16 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 25 | May 6 | Apr 17 |
| Freeze (32°F) | May 5 | Apr 12 | Mar 16 |
| Hard (28°F) | Apr 11 | Mar 9 | Feb 12 |
| Severe (24°F) | Mar 6 | Feb 9 | Dec 22 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 25 | May 17 | May 13 | May 10 | May 6 | May 3 | Apr 30 | Apr 26 | Apr 17 |
| 32°F | May 5 | Apr 30 | Apr 24 | Apr 18 | Apr 12 | Apr 6 | Apr 1 | Mar 26 | Mar 16 |
| 28°F | Apr 11 | Mar 28 | Mar 21 | Mar 14 | Mar 9 | Mar 3 | Feb 27 | Feb 20 | Feb 12 |
| 24°F | Mar 6 | Feb 28 | Feb 21 | Feb 16 | Feb 9 | Jan 31 | Jan 20 | Jan 6 | Dec 22 |
| 20°F | Feb 21 | Feb 12 | Jan 30 | Jan 17 | Jan 7 | Jan 1 | Dec 24 | Dec 16 | Dec 4 |
| 16°F | Jan 25 | Jan 12 | Jan 1 | Dec 31 | Dec 22 | Dec 16 | Dec 11 | Dec 5 | Dec 1 |
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) | Sep 14 | Oct 6 | Oct 27 |
| Freeze (32°F) | Oct 5 | Oct 28 | Nov 21 |
| Hard (28°F) | Oct 25 | Nov 18 | Dec 16 |
| Severe (24°F) | Nov 8 | Dec 8 | Jan 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 14 | Sep 20 | Sep 27 | Oct 2 | Oct 6 | Oct 10 | Oct 15 | Oct 20 | Oct 27 |
| 32°F | Oct 5 | Oct 14 | Oct 20 | Oct 24 | Oct 28 | Nov 1 | Nov 6 | Nov 13 | Nov 21 |
| 28°F | Oct 25 | Nov 1 | Nov 6 | Nov 13 | Nov 18 | Nov 23 | Nov 30 | Dec 5 | Dec 16 |
| 24°F | Nov 8 | Nov 17 | Nov 27 | Dec 2 | Dec 8 | Dec 16 | Dec 24 | Jan 1 | Jan 18 |
| 20°F | Nov 20 | Dec 1 | Dec 7 | Dec 14 | Dec 21 | Dec 30 | Jan 4 | Jan 16 | Feb 7 |
| 16°F | Nov 27 | Dec 1 | Dec 7 | Dec 13 | Dec 17 | Dec 27 | Dec 31 | Jan 6 | Jan 19 |
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: Foster Dam, Or, about 4.6 miles away@if(!empty($station['elevation_ft'])), at 550 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 Cascadia, OR?
On average, the last spring frost (32°F) around Cascadia, OR is about Apr 12. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 16.
When is the first frost in the fall?
The first fall frost around Cascadia, OR typically arrives about Oct 28. 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 Apr 12 on average, or Mar 16 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 197 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 97345 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026