Frost dates for Fenn Ranger Station, ID
At Fenn Ranger Station, the median last spring frost (32°F) is Apr 26 and the median first fall frost is Oct 20, for a typical growing season of 176 days. For a 90% chance that the last frost has passed, wait until May 9. Nearby ZIP codes are in USDA hardiness zones 5b to 7a.
- Apr 26Last spring frost (median)50% chance of 32°F after this date
- May 9Safer planting date10% chance of 32°F after this date
- Oct 20First fall frost (median)50% chance of 32°F by this date
- 176 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 30 | May 10 | May 25 |
| 32°F | Apr 8 | Apr 26 | May 9 |
| 28°F | Mar 10 | Mar 31 | Apr 22 |
| 24°F | Feb 11 | Mar 6 | Mar 29 |
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 18 | Oct 2 | Oct 20 |
| 32°F | Oct 1 | Oct 20 | Nov 5 |
| 28°F | Oct 17 | Nov 3 | Nov 22 |
| 24°F | Oct 24 | Nov 18 | Dec 9 |
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 | 124 days | 144 days | 164 days |
| 32°F | 154 days | 176 days | 201 days |
| 28°F | 185 days | 216 days | 244 days |
| 24°F | 222 days | 254 days | 285 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 |
|---|---|---|---|
| 83552 | 7a | 0 to 5°F | 32 km |
| 83536 | 7a | 0 to 5°F | 40 km |
| 83525 | 5b | -15 to -10°F | 41 km |
| 83530 | 6b | -5 to 0°F | 42 km |
| 83553 | 6b | -5 to 0°F | 43 km |
| 83533 | 6b | -5 to 0°F | 54 km |
| 83539 | 5b | -15 to -10°F | 56 km |
| 83546 | 6a | -10 to -5°F | 57 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 USC00103143, at 46.0931, -115.5356, elevation 476 m (1,560 ft).
- Data quality: Representative (10+ years), 23 years of freeze data.
- Average days per year at or below 32°F: 124.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Lowell Three Rivers (7 km)
- Elk City 1ne (29 km)
- Kooskia 5 SSE (31 km)
- Kamiah (41 km)
- Red River Ranger Station (45 km)
- Grangeville (48 km)
- Pierce (49 km)
- Nezperce (57 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.