Reference Data
Michigan Frost Dates by City
Frost dates vary significantly across Michigan due to the moderating effect of the Great Lakes, elevation changes, and urban heat islands. The data below is based on NOAA 30-year climate normals (1991–2020) for a 32°F threshold.
May 3Statewide Avg Last Spring Frost
Oct 11Statewide Avg First Fall Frost
161 daysAvg Growing Season (Lower MI)
5a–6bZone Range, Lower Peninsula
Lower Peninsula — Last Spring / First Fall Frost
| City | County | Zone | Last Spring Frost | First Fall Frost | Growing Season |
|---|
| Detroit | Wayne | 6b | Apr 14 | Oct 28 | 197 days |
| Ann Arbor | Washtenaw | 6a | Apr 23 | Oct 17 | 177 days |
| Lansing | Ingham | 5b | May 4 | Oct 8 | 157 days |
| Grand Rapids | Kent | 6a | Apr 27 | Oct 19 | 175 days |
| Kalamazoo | Kalamazoo | 6a | Apr 28 | Oct 17 | 172 days |
| Flint | Genesee | 5b | May 5 | Oct 7 | 155 days |
| Saginaw | Saginaw | 6a | May 2 | Oct 12 | 163 days |
| Bay City | Bay | 6a | May 6 | Oct 9 | 156 days |
| Midland | Midland | 5b | May 8 | Oct 5 | 150 days |
| Mount Pleasant | Isabella | 5b | May 9 | Oct 4 | 148 days |
| Traverse City | Grand Traverse | 6a | May 3 | Oct 16 | 166 days |
| Petoskey | Emmet | 5b | May 12 | Oct 8 | 149 days |
| Muskegon | Muskegon | 6a | Apr 24 | Oct 24 | 183 days |
| Holland | Ottawa | 6a | Apr 22 | Oct 24 | 185 days |
| Benton Harbor | Berrien | 6b | Apr 15 | Oct 28 | 196 days |
| Jackson | Jackson | 5b | May 2 | Oct 10 | 161 days |
| Battle Creek | Calhoun | 6a | Apr 29 | Oct 14 | 168 days |
| Monroe | Monroe | 6a | Apr 19 | Oct 22 | 186 days |
| Port Huron | St. Clair | 6a | Apr 25 | Oct 18 | 176 days |
| Alpena | Alpena | 5a | May 19 | Sep 29 | 133 days |
| Gaylord | Otsego | 5a | May 22 | Sep 25 | 126 days |
| Cadillac | Wexford | 5b | May 14 | Oct 2 | 141 days |
| Big Rapids | Mecosta | 5b | May 10 | Oct 3 | 146 days |
| Alma | Gratiot | 5b | May 8 | Oct 6 | 151 days |
Upper Peninsula
| City | County | Zone | Last Spring Frost | First Fall Frost | Growing Season |
|---|
| Marquette | Marquette | 5a | May 17 | Oct 5 | 141 days |
| Escanaba | Delta | 5a | May 15 | Oct 4 | 142 days |
| Sault Ste. Marie | Chippewa | 4b | May 25 | Sep 22 | 120 days |
| Ironwood | Gogebic | 4b | May 28 | Sep 19 | 114 days |
| Houghton | Houghton | 5a | May 20 | Sep 28 | 131 days |
Lakeshore locations (Muskegon, Holland, Benton Harbor, Traverse City) consistently have longer growing seasons due to the Great Lakes thermal buffer. Inland locations at similar latitudes may have 2–4 fewer weeks of frost-free growing time.
Sources: NOAA National Centers for Environmental Information (NCEI), 1991–2020 Climate Normals; USDA Plant Hardiness Zone Map 2023; Michigan State University Extension Climatology Program.
Data compiled and maintained by
Chris Izworski — writer, technologist, and gardener based in Bay City, Michigan.