Frost dates for Foster Dam, OR
At Foster Dam, the median last spring frost (32°F) is Apr 12 and the median first fall frost is Oct 28, for a typical growing season of 197 days. For a 90% chance that the last frost has passed, wait until May 5. Nearby ZIP codes are in USDA hardiness zone 8b.
- Apr 12Last spring frost (median)50% chance of 32°F after this date
- May 5Safer planting date10% chance of 32°F after this date
- Oct 28First fall frost (median)50% chance of 32°F by this date
- 197 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 | Apr 17 | May 6 | May 25 |
| 32°F | Mar 16 | Apr 12 | May 5 |
| 28°F | Feb 12 | Mar 9 | Apr 11 |
| 24°F | Dec 22 | Feb 9 | Mar 6 |
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 | Sep 14 | Oct 6 | Oct 27 |
| 32°F | Oct 5 | Oct 28 | Nov 21 |
| 28°F | Oct 25 | Nov 18 | Dec 16 |
| 24°F | Nov 8 | Dec 8 | Jan 18 |
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 | 125 days | 153 days | 182 days |
| 32°F | 165 days | 197 days | 233 days |
| 28°F | 214 days | 252 days | 296 days |
| 24°F | 264 days | 313 days | 357 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 95% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 97386 | 8b | 15 to 20°F | 7 km |
| 97345 | 8b | 15 to 20°F | 7 km |
| 97336 | 8b | 15 to 20°F | 16 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 USC00353047, at 44.4139, -122.6728, elevation 168 m (550 ft).
- Data quality: Standard (24+ years of data), 25 years of freeze data.
- Average days per year at or below 32°F: 55.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Cascadia (15 km)
- Lebanon (22 km)
- Lacomb 3 NNE (24 km)
- Leaburg 1 SW (35 km)
- Stayton (43 km)
- Cougar Dam (47 km)
- Corvallis State Univ (48 km)
- Detroit Dam (48 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.