Last spring frost
May 15
Frost Dates for Idanha, OR
First fall frost
Sep 30
Growing season
134 days
Hardiness zone
7b
In an average year around Idanha, OR, the last spring frost (32°F) is about May 15 and the first fall frost is about Sep 30, giving roughly a 134-day growing season. To be safe most years, wait until Apr 29 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%) |
|---|---|---|---|
| Freeze (32°F) | Jun 11 | May 15 | Apr 29 |
| Hard (28°F) | May 14 | Apr 24 | Mar 31 |
| Severe (24°F) | Apr 10 | Mar 14 | Feb 19 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 11 | May 31 | May 25 | May 20 | May 15 | May 11 | May 8 | May 3 | Apr 29 |
| 28°F | May 14 | May 4 | Apr 30 | Apr 28 | Apr 24 | Apr 19 | Apr 14 | Apr 9 | Mar 31 |
| 24°F | Apr 10 | Apr 1 | Mar 25 | Mar 19 | Mar 14 | Mar 9 | Mar 5 | Feb 28 | Feb 19 |
| 20°F | Mar 14 | Mar 7 | Mar 2 | Feb 26 | Feb 21 | Feb 15 | Feb 7 | Jan 29 | Jan 10 |
| 16°F | Mar 5 | Feb 25 | Feb 18 | Feb 10 | Jan 31 | Jan 19 | Jan 12 | Jan 2 | Dec 12 |
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%) |
|---|---|---|---|
| Freeze (32°F) | Sep 10 | Sep 30 | Oct 18 |
| Hard (28°F) | Oct 1 | Oct 23 | Nov 14 |
| Severe (24°F) | Oct 23 | Nov 14 | Dec 7 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Sep 10 | Sep 17 | Sep 21 | Sep 25 | Sep 30 | Oct 3 | Oct 6 | Oct 11 | Oct 18 |
| 28°F | Oct 1 | Oct 7 | Oct 13 | Oct 18 | Oct 23 | Oct 27 | Nov 1 | Nov 6 | Nov 14 |
| 24°F | Oct 23 | Oct 31 | Nov 4 | Nov 9 | Nov 14 | Nov 20 | Nov 25 | Nov 30 | Dec 7 |
| 20°F | Nov 7 | Nov 15 | Nov 23 | Nov 28 | Dec 2 | Dec 7 | Dec 15 | Dec 24 | Jan 5 |
| 16°F | Nov 20 | Nov 29 | Dec 4 | Dec 11 | Dec 21 | Dec 30 | Jan 6 | Jan 15 | Feb 3 |
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: Marion Forks Fish Hatchery, Or, about 9.4 miles away@if(!empty($station['elevation_ft'])), at 2,475 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 Idanha, OR?
On average, the last spring frost (32°F) around Idanha, OR is about May 15. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 29.
When is the first frost in the fall?
The first fall frost around Idanha, OR typically arrives about Sep 30. 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 May 15 on average, or Apr 29 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 134 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 97342 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026