Frost dates for Richfield, ID
At Richfield, the median last spring frost (32°F) is May 24 and the median first fall frost is Sep 26, for a typical growing season of 123 days. For a 90% chance that the last frost has passed, wait until Jun 14. Nearby ZIP codes are in USDA hardiness zone 6a.
- May 24Last spring frost (median)50% chance of 32°F after this date
- Jun 14Safer planting date10% chance of 32°F after this date
- Sep 26First fall frost (median)50% chance of 32°F by this date
- 123 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 23 | Jun 11 | Jun 27 |
| 32°F | May 6 | May 24 | Jun 14 |
| 28°F | Apr 23 | May 8 | May 28 |
| 24°F | Apr 4 | Apr 25 | 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 | Sep 1 | Sep 14 | Sep 27 |
| 32°F | Sep 10 | Sep 26 | Oct 10 |
| 28°F | Sep 23 | Oct 7 | Oct 22 |
| 24°F | Oct 5 | Oct 20 | Nov 3 |
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 | 71 days | 93 days | 117 days |
| 32°F | 97 days | 123 days | 145 days |
| 28°F | 128 days | 152 days | 174 days |
| 24°F | 156 days | 178 days | 201 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 |
|---|---|---|---|
| 83349 | 6a | -10 to -5°F | 7 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 USC00107673, at 43.0517, -114.1550, elevation 1313 m (4,309 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 185.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Shoshone 1 WNW (25 km)
- Picabo (29 km)
- Jerome Co Airport (44 km)
- Jerome (46 km)
- Bellevue (47 km)
- Hazelton (51 km)
- Twin Falls-Kmvt (58 km)
- Twin Falls 6 E (58 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.