Last spring frost
May 10
Frost Dates for Denio, OR
First fall frost
Oct 7
Growing season
145 days
Hardiness zone
6b
In an average year around Denio, OR, the last spring frost (32°F) is about May 10 and the first fall frost is about Oct 7, giving roughly a 145-day growing season. To be safe most years, wait until Apr 25 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) | Jun 21 | Jun 4 | May 11 |
| Freeze (32°F) | Jun 3 | May 10 | Apr 25 |
| Hard (28°F) | May 15 | Apr 27 | Apr 9 |
| Severe (24°F) | May 2 | Apr 11 | Mar 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 21 | Jun 16 | Jun 12 | Jun 8 | Jun 4 | Jun 1 | May 25 | May 19 | May 11 |
| 32°F | Jun 3 | May 26 | May 20 | May 15 | May 10 | May 6 | May 2 | Apr 29 | Apr 25 |
| 28°F | May 15 | May 8 | May 3 | Apr 30 | Apr 27 | Apr 24 | Apr 20 | Apr 16 | Apr 9 |
| 24°F | May 2 | Apr 26 | Apr 21 | Apr 16 | Apr 11 | Apr 7 | Apr 2 | Mar 28 | Mar 18 |
| 20°F | Apr 19 | Apr 8 | Apr 2 | Mar 27 | Mar 21 | Mar 15 | Mar 9 | Mar 3 | Feb 25 |
| 16°F | Mar 31 | Mar 17 | Mar 9 | Mar 4 | Feb 28 | Feb 24 | Feb 20 | Feb 15 | Feb 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) | Sep 8 | Sep 25 | Oct 9 |
| Freeze (32°F) | Sep 21 | Oct 7 | Oct 21 |
| Hard (28°F) | Oct 4 | Oct 19 | Nov 3 |
| Severe (24°F) | Oct 16 | Oct 30 | Nov 13 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 8 | Sep 14 | Sep 18 | Sep 21 | Sep 25 | Sep 28 | Oct 1 | Oct 4 | Oct 9 |
| 32°F | Sep 21 | Sep 27 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 21 |
| 28°F | Oct 4 | Oct 9 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 30 | Nov 3 |
| 24°F | Oct 16 | Oct 20 | Oct 23 | Oct 27 | Oct 30 | Nov 2 | Nov 4 | Nov 8 | Nov 13 |
| 20°F | Oct 24 | Oct 29 | Nov 2 | Nov 5 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 25 |
| 16°F | Nov 2 | Nov 9 | Nov 13 | Nov 16 | Nov 20 | Nov 24 | Nov 26 | Nov 30 | Dec 5 |
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: Fields, Or, about 21.6 miles away@if(!empty($station['elevation_ft'])), at 4,227 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 Denio, OR?
On average, the last spring frost (32°F) around Denio, OR is about May 10. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 25.
When is the first frost in the fall?
The first fall frost around Denio, OR typically arrives about Oct 7. 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 10 on average, or Apr 25 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 145 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 97721 Planting calendar → Oregon frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026