Frost dates for Twin Falls Sun Valley Regional Airport, ID
At Twin Falls Sun Valley Regional Airport, the median last spring frost (32°F) is May 9 and the median first fall frost is Oct 4, for a typical growing season of 147 days. For a 90% chance that the last frost has passed, wait until May 28. Nearby ZIP codes are in USDA hardiness zone 6b.
- May 9Last spring frost (median)50% chance of 32°F after this date
- May 28Safer planting date10% chance of 32°F after this date
- Oct 4First fall frost (median)50% chance of 32°F by this date
- 147 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 10 | May 28 | Jun 16 |
| 32°F | Apr 25 | May 9 | May 28 |
| 28°F | Apr 8 | Apr 25 | May 11 |
| 24°F | Mar 12 | Apr 5 | Apr 25 |
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 9 | Sep 23 | Oct 5 |
| 32°F | Sep 20 | Oct 4 | Oct 20 |
| 28°F | Sep 29 | Oct 15 | Oct 30 |
| 24°F | Oct 8 | Oct 26 | Nov 12 |
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 | 93 days | 115 days | 139 days |
| 32°F | 122 days | 147 days | 170 days |
| 28°F | 148 days | 174 days | 198 days |
| 24°F | 178 days | 204 days | 233 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 |
|---|---|---|---|
| 83301 | 6b | -5 to 0°F | 10 km |
| 83341 | 6b | -5 to 0°F | 11 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 USW00094178, at 42.4819, -114.4869, elevation 1265 m (4,151 ft).
- Data quality: Representative (10+ years), 23 years of freeze data.
- Average days per year at or below 32°F: 139.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Twin Falls-Kmvt (11 km)
- Twin Falls 6 E (14 km)
- Buhl #2 (25 km)
- Jerome Co Airport (27 km)
- Jerome (28 km)
- Hazelton (31 km)
- Castleford 2 N (32 km)
- Shoshone 1 WNW (51 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.