Frost dates for Idaho Falls 46 W, ID
At Idaho Falls 46 W, 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 89 days. For a 90% chance that the last frost has passed, wait until Jul 1. Nearby ZIP codes are in USDA hardiness zones 4b to 5b.
- 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
- 89 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 20 | Jun 11 | Jul 1 |
| 28°F | May 5 | May 23 | Jun 16 |
| 24°F | Apr 23 | May 6 | May 27 |
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 24 | Sep 6 | Sep 21 |
| 28°F | Sep 3 | Sep 18 | Oct 3 |
| 24°F | Sep 13 | Sep 30 | Oct 15 |
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 | 39 days | 63 days | 83 days |
| 32°F | 64 days | 89 days | 113 days |
| 28°F | 90 days | 118 days | 141 days |
| 24°F | 119 days | 144 days | 164 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 |
|---|---|---|---|
| 83213 | 5a | -20 to -15°F | 35 km |
| 83262 | 5b | -15 to -10°F | 36 km |
| 83244 | 5a | -20 to -15°F | 41 km |
| 83221 | 5b | -15 to -10°F | 44 km |
| 83255 | 5a | -20 to -15°F | 46 km |
| 83277 | 5b | -15 to -10°F | 55 km |
| 83444 | 5a | -20 to -15°F | 56 km |
| 83450 | 4b | -25 to -20°F | 56 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 USW00094143, at 43.5317, -112.9422, elevation 1505 m (4,938 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 208.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Howe (28 km)
- Arco (31 km)
- Arco 17 SW (50 km)
- Craters Of The Moon (50 km)
- Blackfoot Fire Dept (61 km)
- Monteview (63 km)
- Aberdeen Exp. Station (65 km)
- Mackay Lost River Ranger Station (69 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.