Frost dates for Riggins, ID
At Riggins, the median last spring frost (32°F) is May 6 and the median first fall frost is Oct 9, for a typical growing season of 155 days. For a 90% chance that the last frost has passed, wait until May 26. Nearby ZIP codes are in USDA hardiness zones 6a to 7a.
- May 6Last spring frost (median)50% chance of 32°F after this date
- May 26Safer planting date10% chance of 32°F after this date
- Oct 9First fall frost (median)50% chance of 32°F by this date
- 155 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 | May 11 | May 29 | Jun 20 |
| 32°F | Apr 23 | May 6 | May 26 |
| 28°F | Mar 31 | Apr 18 | May 5 |
| 24°F | Mar 6 | Mar 27 | Apr 17 |
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 10 | Sep 27 | Oct 12 |
| 32°F | Sep 24 | Oct 9 | Oct 26 |
| 28°F | Oct 7 | Oct 22 | Nov 7 |
| 24°F | Oct 18 | Nov 3 | Nov 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 | 91 days | 119 days | 141 days |
| 32°F | 130 days | 155 days | 176 days |
| 28°F | 163 days | 185 days | 209 days |
| 24°F | 196 days | 225 days | 253 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 83547 | 6b | -5 to 0°F | 6 km |
| 83549 | 6b | -5 to 0°F | 10 km |
| 83654 | 6a | -10 to -5°F | 18 km |
| 83542 | 7a | 0 to 5°F | 24 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 USC00107706, at 45.3542, -116.3950, elevation 627 m (2,056 ft).
- Data quality: Representative (10+ years), 17 years of freeze data.
- Average days per year at or below 32°F: 92.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- New Meadows Ranger Station (43 km)
- McCall Airport (57 km)
- McCall (57 km)
- Warren (57 km)
- Council (68 km)
- Grangeville (69 km)
- Brownlee Dam (70 km)
- Cottonwood 2 WSW (76 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.