Frost dates for Primghar, IA
At Primghar, the median last spring frost (32°F) is Apr 29 and the median first fall frost is Oct 10, for a typical growing season of 163 days. For a 90% chance that the last frost has passed, wait until May 11. Nearby ZIP codes are in USDA hardiness zone 5a.
- Apr 29Last spring frost (median)50% chance of 32°F after this date
- May 11Safer planting date10% chance of 32°F after this date
- Oct 10First fall frost (median)50% chance of 32°F by this date
- 163 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 24 | May 8 | May 22 |
| 32°F | Apr 13 | Apr 29 | May 11 |
| 28°F | Apr 3 | Apr 18 | May 1 |
| 24°F | Mar 25 | Apr 9 | Apr 22 |
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 19 | Oct 1 | Oct 14 |
| 32°F | Sep 26 | Oct 10 | Oct 23 |
| 28°F | Oct 5 | Oct 21 | Nov 4 |
| 24°F | Oct 15 | Oct 30 | Nov 13 |
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 | 128 days | 146 days | 163 days |
| 32°F | 144 days | 163 days | 184 days |
| 28°F | 162 days | 185 days | 204 days |
| 24°F | 183 days | 202 days | 223 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 |
|---|---|---|---|
| 51245 | 5a | -20 to -15°F | 2 km |
| 51231 | 5a | -20 to -15°F | 9 km |
| 51046 | 5a | -20 to -15°F | 14 km |
| 51058 | 5a | -20 to -15°F | 16 km |
| 51009 | 5a | -20 to -15°F | 17 km |
| 51022 | 5a | -20 to -15°F | 21 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 USC00136800, at 43.0864, -95.6292, elevation 463 m (1,520 ft).
- Data quality: Standard (24+ years of data), 26 years of freeze data.
- Average days per year at or below 32°F: 153.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Sanborn (11 km)
- Sheldon (21 km)
- Spencer Muni Airport (36 km)
- Sibley (37 km)
- Cherokee (37 km)
- Spencer 1 N (40 km)
- Sioux Center 2 SE (43 km)
- Lake Park (47 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.