Michigan weather in September
The state broadly agrees with itself in September: afternoons run 71° in Traverse City and 70° in Mackinac Island, with everywhere else in between.
Based on 2 weather stations. Two stations in the vacation north — Detroit and the state’s southern tier run warmer than what’s here, and the Upper Peninsula colder.
Northwest Lower Michigan
Highs near 71°, nights around 50°, and 3.6 in of rain in a typical September.
| Place | Highs / lows | Wet days | The short version |
|---|---|---|---|
| Traverse City | 71° / 50° | 7 | Harvest light, warm afternoons, and the tour buses gone. |
The Straits
Highs near 70°, nights around 45°, and 3.4 in of rain in a typical September.
| Place | Highs / lows | Wet days | The short version |
|---|---|---|---|
| Mackinac Island | 70° / 45° | 8 | Everything still open, and a fraction of the people. |
Each place above has its own page for the full story — what the month feels like, what to pack, and whether the timing is right.