Frost dates for Two Harbors 7nw, MN
At Two Harbors 7nw, the median last spring frost (32°F) is May 27 and the median first fall frost is Sep 23, for a typical growing season of 117 days. For a 90% chance that the last frost has passed, wait until Jun 10. Nearby ZIP codes are in USDA hardiness zones 3b to 4b.
- May 27Last spring frost (median)50% chance of 32°F after this date
- Jun 10Safer planting date10% chance of 32°F after this date
- Sep 23First fall frost (median)50% chance of 32°F by this date
- 117 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 27 | Jun 8 | Jun 23 |
| 32°F | May 14 | May 27 | Jun 10 |
| 28°F | Apr 28 | May 12 | May 27 |
| 24°F | Apr 16 | Apr 29 | May 14 |
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 | Aug 27 | Sep 11 | Sep 25 |
| 32°F | Sep 7 | Sep 23 | Oct 7 |
| 28°F | Sep 18 | Oct 5 | Oct 20 |
| 24°F | Oct 2 | Oct 19 | 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 | 73 days | 93 days | 112 days |
| 32°F | 97 days | 117 days | 139 days |
| 28°F | 123 days | 142 days | 166 days |
| 24°F | 146 days | 171 days | 191 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 55616 | 3b | -35 to -30°F | 14 km |
| 55609 | 4b | -25 to -20°F | 19 km |
| 55602 | 3b | -35 to -30°F | 27 km |
| 55804 | 4b | -25 to -20°F | 28 km |
| 55601 | 4a | -30 to -25°F | 29 km |
| 55803 | 4a | -30 to -25°F | 29 km |
| 55614 | 4a | -30 to -25°F | 35 km |
| 55812 | 4b | -25 to -20°F | 45 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 USC00218421, at 47.1253, -91.7067, elevation 413 m (1,355 ft).
- Data quality: Representative (10+ years), 22 years of freeze data.
- Average days per year at or below 32°F: 196.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Two Harbors (11 km)
- Brimson 2s (18 km)
- Island Lake 4e (30 km)
- Duluth Harbor Station (49 km)
- Duluth (50 km)
- Duluth NWS (50 km)
- Wolf Ridge Elc (52 km)
- Isabella 14w (52 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.