Frost dates for St. Ignace Mackinac Br, MI
At St. Ignace Mackinac Br, the median last spring frost (32°F) is May 7 and the median first fall frost is Oct 23, for a typical growing season of 167 days. For a 90% chance that the last frost has passed, wait until May 22. Nearby ZIP codes are in USDA hardiness zone 5b.
- May 7Last spring frost (median)50% chance of 32°F after this date
- May 22Safer planting date10% chance of 32°F after this date
- Oct 23First fall frost (median)50% chance of 32°F by this date
- 167 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 6 | May 20 | Jun 2 |
| 32°F | Apr 25 | May 7 | May 22 |
| 28°F | Apr 11 | Apr 25 | May 10 |
| 24°F | Apr 1 | Apr 13 | Apr 28 |
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 28 | Oct 9 | Oct 25 |
| 32°F | Oct 6 | Oct 23 | Nov 6 |
| 28°F | Oct 21 | Nov 3 | Nov 18 |
| 24°F | Nov 2 | Nov 15 | Nov 29 |
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 | 124 days | 142 days | 162 days |
| 32°F | 146 days | 167 days | 187 days |
| 28°F | 171 days | 191 days | 210 days |
| 24°F | 195 days | 214 days | 234 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 |
|---|---|---|---|
| 49701 | 5b | -15 to -10°F | 12 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 USC00207274, at 45.8489, -84.7228, elevation 181 m (595 ft).
- Data quality: Representative (10+ years), 19 years of freeze data.
- Average days per year at or below 32°F: 148.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- St. Ignace (1 km)
- Moran (18 km)
- Cheboygan (29 km)
- Pellston Airport #2 (31 km)
- Pellston Regional Airport (32 km)
- Cross Village 1e (32 km)
- Rudyard 5se (41 km)
- Trout Lake 1sw (44 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.