Frost dates for Benson, MN
At Benson, the median last spring frost (32°F) is May 4 and the median first fall frost is Oct 3, for a typical growing season of 151 days. For a 90% chance that the last frost has passed, wait until May 17. Nearby ZIP codes are in USDA hardiness zone 4b.
- May 4Last spring frost (median)50% chance of 32°F after this date
- May 17Safer planting date10% chance of 32°F after this date
- Oct 3First fall frost (median)50% chance of 32°F by this date
- 151 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 30 | May 13 | May 26 |
| 32°F | Apr 22 | May 4 | May 17 |
| 28°F | Apr 11 | Apr 26 | May 8 |
| 24°F | Apr 3 | Apr 15 | Apr 30 |
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 14 | Sep 26 | Oct 6 |
| 32°F | Sep 21 | Oct 3 | Oct 15 |
| 28°F | Sep 28 | Oct 12 | Oct 26 |
| 24°F | Oct 7 | Oct 23 | Nov 4 |
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 | 117 days | 134 days | 151 days |
| 32°F | 132 days | 151 days | 170 days |
| 28°F | 150 days | 171 days | 188 days |
| 24°F | 170 days | 189 days | 208 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 |
|---|---|---|---|
| 56215 | 4b | -25 to -20°F | 4 km |
| 56226 | 4b | -25 to -20°F | 11 km |
| 56231 | 4b | -25 to -20°F | 12 km |
| 56271 | 4b | -25 to -20°F | 18 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 USC00210667, at 45.3167, -95.6167, elevation 314 m (1,030 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 168.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Milan 1nw (33 km)
- Morris W Cntrl Rsch & Outreach (36 km)
- Glenwood 2wnw (40 km)
- Artichoke Lake 1 E (41 km)
- Montevideo 1sw (44 km)
- Willmar 5n (46 km)
- Willmar Wastewater Plant (51 km)
- New London (53 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.