Frost dates for Riley 10 WSW, OR
At Riley 10 WSW, the median last spring frost (32°F) is Jun 11 and the median first fall frost is Sep 11, for a typical growing season of 87 days. For a 90% chance that the last frost has passed, wait until Jul 3. Nearby ZIP codes are in USDA hardiness zones 6a to 6b.
- Jun 11Last spring frost (median)50% chance of 32°F after this date
- Jul 3Safer planting date10% chance of 32°F after this date
- Sep 11First fall frost (median)50% chance of 32°F by this date
- 87 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 |
|---|---|---|---|
| 32°F | May 24 | Jun 11 | Jul 3 |
| 28°F | May 6 | May 23 | Jun 13 |
| 24°F | Apr 24 | May 6 | May 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 |
|---|---|---|---|
| 32°F | Aug 23 | Sep 11 | Sep 24 |
| 28°F | Sep 7 | Sep 23 | Oct 8 |
| 24°F | Sep 23 | Oct 7 | Oct 23 |
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 | 35 days | 62 days | 87 days |
| 32°F | 57 days | 87 days | 112 days |
| 28°F | 93 days | 123 days | 147 days |
| 24°F | 130 days | 153 days | 175 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 97758 | 6a | -10 to -5°F | 7 km |
| 97738 | 6a | -10 to -5°F | 43 km |
| 97720 | 6a | -10 to -5°F | 65 km |
| 97712 | 6a | -10 to -5°F | 67 km |
| 97641 | 6a | -10 to -5°F | 71 km |
| 97751 | 6a | -10 to -5°F | 74 km |
| 97752 | 6a | -10 to -5°F | 84 km |
| 97820 | 6b | -5 to 0°F | 85 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 USW00004128, at 43.4711, -119.6917, elevation 1397 m (4,583 ft).
- Data quality: Representative (10+ years), 17 years of freeze data.
- Average days per year at or below 32°F: 203.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Squaw Butte-Northern Great Bas (3 km)
- O O Rch (37 km)
- Burns Muni Airport (61 km)
- Alkali Lake (61 km)
- Barnes Station (68 km)
- Malheur Refuge HQ (72 km)
- Paulina (78 km)
- Brothers (82 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.