Last spring frost
Jun 7
Frost Dates for Wallowa, OR
First fall frost
Sep 9
Growing season
91 days
Hardiness zone
6b
In an average year around Wallowa, OR, the last spring frost (32°F) is about Jun 7 and the first fall frost is about Sep 9, giving roughly a 91-day growing season. To be safe most years, wait until May 14 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) | Jul 7 | Jun 7 | May 14 |
| Hard (28°F) | May 29 | May 11 | Apr 29 |
| Severe (24°F) | May 11 | Apr 28 | Apr 11 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jul 7 | Jun 23 | Jun 18 | Jun 12 | Jun 7 | Jun 1 | May 27 | May 22 | May 14 |
| 28°F | May 29 | May 22 | May 17 | May 13 | May 11 | May 8 | May 6 | May 2 | Apr 29 |
| 24°F | May 11 | May 7 | May 4 | May 1 | Apr 28 | Apr 25 | Apr 21 | Apr 17 | Apr 11 |
| 20°F | Apr 27 | Apr 20 | Apr 16 | Apr 10 | Apr 6 | Apr 1 | Mar 28 | Mar 21 | Mar 13 |
| 16°F | Apr 3 | Mar 26 | Mar 18 | Mar 13 | Mar 8 | Mar 4 | Mar 1 | Feb 25 | Feb 16 |
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) | Aug 24 | Sep 9 | Sep 27 |
| Hard (28°F) | Sep 5 | Sep 24 | Oct 8 |
| Severe (24°F) | Sep 19 | Oct 5 | Oct 21 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 24 | Aug 31 | Sep 3 | Sep 6 | Sep 9 | Sep 12 | Sep 16 | Sep 21 | Sep 27 |
| 28°F | Sep 5 | Sep 11 | Sep 16 | Sep 21 | Sep 24 | Sep 28 | Oct 1 | Oct 4 | Oct 8 |
| 24°F | Sep 19 | Sep 26 | Sep 30 | Oct 3 | Oct 5 | Oct 8 | Oct 12 | Oct 16 | Oct 21 |
| 20°F | Oct 2 | Oct 7 | Oct 12 | Oct 16 | Oct 20 | Oct 23 | Oct 27 | Oct 31 | Nov 7 |
| 16°F | Oct 16 | Oct 22 | Oct 27 | Oct 31 | Nov 4 | Nov 9 | Nov 14 | Nov 20 | Nov 26 |
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: Wallowa, Or, about 5.5 miles away@if(!empty($station['elevation_ft'])), at 2,923 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 Wallowa, OR?
On average, the last spring frost (32°F) around Wallowa, OR is about Jun 7. In cooler years it can run later, so for a safer bet many gardeners wait until May 14.
When is the first frost in the fall?
The first fall frost around Wallowa, OR typically arrives about Sep 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 Jun 7 on average, or May 14 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 91 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 97885 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026