Frost dates for Sanborn, IA
At Sanborn, the median last spring frost (32°F) is May 1 and the median first fall frost is Oct 7, for a typical growing season of 160 days. For a 90% chance that the last frost has passed, wait until May 13. Nearby ZIP codes are in USDA hardiness zone 5a.
- May 1Last spring frost (median)50% chance of 32°F after this date
- May 13Safer planting date10% chance of 32°F after this date
- Oct 7First fall frost (median)50% chance of 32°F by this date
- 160 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 | Apr 27 | May 8 | May 22 |
| 32°F | Apr 16 | May 1 | May 13 |
| 28°F | Apr 6 | Apr 20 | May 4 |
| 24°F | Mar 29 | Apr 11 | Apr 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 |
|---|---|---|---|
| 36°F | Sep 15 | Sep 28 | Oct 11 |
| 32°F | Sep 23 | Oct 7 | Oct 20 |
| 28°F | Oct 1 | Oct 17 | Oct 31 |
| 24°F | Oct 13 | Oct 26 | Nov 8 |
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 | 123 days | 142 days | 160 days |
| 32°F | 141 days | 160 days | 179 days |
| 28°F | 158 days | 179 days | 199 days |
| 24°F | 176 days | 197 days | 218 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 |
|---|---|---|---|
| 51248 | 5a | -20 to -15°F | 3 km |
| 51350 | 5a | -20 to -15°F | 15 km |
| 51346 | 5a | -20 to -15°F | 17 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 USC00137386, at 43.1792, -95.6603, elevation 473 m (1,551 ft).
- Data quality: Standard (24+ years of data), 27 years of freeze data.
- Average days per year at or below 32°F: 166.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Primghar (11 km)
- Sheldon (16 km)
- Sibley (26 km)
- Spencer Muni Airport (37 km)
- Lake Park (40 km)
- Spencer 1 N (42 km)
- Sioux Center 2 SE (42 km)
- Milford 4 NW (45 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.