Frost dates for Detroit Dam, OR
At Detroit Dam, the median last spring frost (32°F) is Mar 9 and the median first fall frost is Dec 3, for a typical growing season of 270 days. For a 90% chance that the last frost has passed, wait until Apr 8. Nearby ZIP codes are in USDA hardiness zone 8b.
- Mar 9Last spring frost (median)50% chance of 32°F after this date
- Apr 8Safer planting date10% chance of 32°F after this date
- Dec 3First fall frost (median)50% chance of 32°F by this date
- 270 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Mar 26 | Apr 17 | May 12 |
| 32°F | Feb 2 | Mar 9 | Apr 8 |
| 28°F | Dec 23 | Feb 5 | Mar 8 |
| 24°F | Dec 10 | Jan 16 | Feb 24 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Oct 25 | Nov 11 | Dec 2 |
| 32°F | Nov 8 | Dec 3 | Jan 4 |
| 28°F | Nov 22 | Dec 26 | Feb 5 |
| 24°F | Dec 1 | Jan 1 | Feb 16 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 175 days | 207 days | 237 days |
| 32°F | 227 days | 270 days | 311 days |
| 28°F | 284 days | 327 days | 365 days |
| 24°F | 312 days | 362 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 84% |
| 24°F | 54% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 97346 | 8b | 15 to 20°F | 11 km |
| 97358 | 8b | 15 to 20°F | 15 km |
| 97360 | 8b | 15 to 20°F | 18 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00352292, at 44.7242, -122.2547, elevation 372 m (1,220 ft).
- Data quality: Representative (10+ years), 22 years of freeze data.
- Average days per year at or below 32°F: 46.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Marion Forks Fish Hatchery (27 km)
- Scotts Mills 9 SE (33 km)
- Silver Creek Falls (35 km)
- Lacomb 3 NNE (38 km)
- Santiam Junction (40 km)
- Cascadia (41 km)
- Stayton (45 km)
- Three Lynx (47 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.