Frost dates for Le Mars, IA
At Le Mars, the median last spring frost (32°F) is Apr 30 and the median first fall frost is Oct 4, for a typical growing season of 157 days. For a 90% chance that the last frost has passed, wait until May 12. Nearby ZIP codes are in USDA hardiness zone 5a.
- Apr 30Last spring frost (median)50% chance of 32°F after this date
- May 12Safer planting date10% chance of 32°F after this date
- Oct 4First fall frost (median)50% chance of 32°F by this date
- 157 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 28 | May 9 | May 22 |
| 32°F | Apr 17 | Apr 30 | May 12 |
| 28°F | Apr 5 | Apr 20 | May 2 |
| 24°F | Mar 29 | Apr 10 | 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 13 | Sep 27 | Oct 9 |
| 32°F | Sep 21 | Oct 4 | Oct 19 |
| 28°F | Sep 29 | Oct 16 | Oct 30 |
| 24°F | Oct 11 | Oct 27 | Nov 9 |
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 | 121 days | 139 days | 157 days |
| 32°F | 138 days | 157 days | 175 days |
| 28°F | 157 days | 178 days | 197 days |
| 24°F | 177 days | 197 days | 216 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 |
|---|---|---|---|
| 51031 | 5a | -20 to -15°F | 4 km |
| 51008 | 5a | -20 to -15°F | 10 km |
| 51050 | 5a | -20 to -15°F | 16 km |
| 51038 | 5a | -20 to -15°F | 16 km |
| 51024 | 5a | -20 to -15°F | 20 km |
| 51028 | 5a | -20 to -15°F | 24 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 USC00134735, at 42.7817, -96.1458, elevation 364 m (1,195 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 160.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Sioux Center 2 SE (30 km)
- Hawarden (37 km)
- Sioux City Ang (47 km)
- Sioux City Gateway Airport (47 km)
- Cherokee (50 km)
- Sheldon (50 km)
- Primghar (54 km)
- Holstein (59 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.