Frost dates for Idaho Falls Fanning Field, ID
At Idaho Falls Fanning Field, the median last spring frost (32°F) is May 23 and the median first fall frost is Sep 20, for a typical growing season of 114 days. For a 90% chance that the last frost has passed, wait until Jun 13. Nearby ZIP codes are in USDA hardiness zone 5b.
- May 23Last spring frost (median)50% chance of 32°F after this date
- Jun 13Safer planting date10% chance of 32°F after this date
- Sep 20First fall frost (median)50% chance of 32°F by this date
- 114 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 28 | Jun 14 | Jul 2 |
| 32°F | May 7 | May 23 | Jun 13 |
| 28°F | Apr 23 | May 7 | May 23 |
| 24°F | Apr 4 | Apr 24 | May 10 |
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 | Aug 20 | Sep 5 | Sep 22 |
| 32°F | Sep 1 | Sep 20 | Oct 4 |
| 28°F | Sep 15 | Oct 2 | Oct 16 |
| 24°F | Sep 28 | Oct 14 | Oct 28 |
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 | 56 days | 79 days | 103 days |
| 32°F | 88 days | 114 days | 139 days |
| 28°F | 124 days | 146 days | 167 days |
| 24°F | 151 days | 172 days | 196 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 |
|---|---|---|---|
| 83402 | 5b | -15 to -10°F | 9 km |
| 83274 | 5b | -15 to -10°F | 19 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 USW00024145, at 43.5164, -112.0672, elevation 1441 m (4,729 ft).
- Data quality: Representative (10+ years), 23 years of freeze data.
- Average days per year at or below 32°F: 182.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Idaho Falls - Kifi (4 km)
- Rigby (22 km)
- Idaho Falls 16 SE (30 km)
- Rexburg Byu Idaho (39 km)
- Rexburg Madison Co Airport (41 km)
- Blackfoot Fire Dept (43 km)
- Sugar City (49 km)
- Hamer 4 NW (52 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.