Frost dates for O O Rch, OR
At O O Rch, the median last spring frost (32°F) is Jun 11 and the median first fall frost is Sep 6, for a typical growing season of 88 days. For a 90% chance that the last frost has passed, wait until Jul 1. 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 1Safer planting date10% chance of 32°F after this date
- Sep 6First fall frost (median)50% chance of 32°F by this date
- 88 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 18 | Jun 11 | Jul 1 |
| 28°F | Apr 29 | May 22 | Jun 20 |
| 24°F | Apr 4 | May 1 | May 30 |
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 19 | Sep 6 | Sep 22 |
| 28°F | Sep 3 | Sep 19 | Oct 7 |
| 24°F | Sep 13 | Oct 4 | Oct 25 |
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 | 33 days | 59 days | 82 days |
| 32°F | 61 days | 88 days | 116 days |
| 28°F | 88 days | 122 days | 153 days |
| 24°F | 124 days | 158 days | 191 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 |
|---|---|---|---|
| 97738 | 6a | -10 to -5°F | 26 km |
| 97758 | 6a | -10 to -5°F | 42 km |
| 97720 | 6a | -10 to -5°F | 48 km |
| 97722 | 6a | -10 to -5°F | 56 km |
| 97736 | 6b | -5 to 0°F | 75 km |
| 97732 | 6a | -10 to -5°F | 83 km |
| 97904 | 6a | -10 to -5°F | 95 km |
| 97820 | 6b | -5 to 0°F | 97 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 USC00356302, at 43.2783, -119.3111, elevation 1261 m (4,136 ft).
- Data quality: Representative (10+ years), 17 years of freeze data.
- Average days per year at or below 32°F: 197.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Riley 10 WSW (37 km)
- Malheur Refuge HQ (38 km)
- Squaw Butte-Northern Great Bas (40 km)
- Burns Muni Airport (45 km)
- Alkali Lake (65 km)
- Hart Mountain Refuge (86 km)
- Riverside 7 SSW (90 km)
- Drewsey (96 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.