Normally Oct 30
That is the whole estimate, and it is the weather rather than a resort. No opening date for any resort here is on file yet, so there is nothing to project from. The chart and the tiles below are the same ones the Minnesota page runs on, taken at Ironwood, Marquette and Sault Ste Marie instead of at resorts. The curve is Ironwood.
Snow guns need a wet-bulb temperature under 28°F. The mean at Ironwood does not get there until Nov 12, but the first workable window normally arrives on Oct 30. Resorts open on those early cold snaps rather than on the average.
No snowmaking weather in the next 16 days. The coldest any of these gets is 47.2° at Ironwood.
47.2°
Coldest wet bulb the 16-day forecast reaches at Ironwood.
51.3°
Coldest wet bulb the 16-day forecast reaches at Marquette.
52.3°
Coldest wet bulb the 16-day forecast reaches at Sault Ste Marie.
Wet-bulb forecast from Open-Meteo, updated twice a day. Guns can run under 28°.
We need somebody to help find opening dates, closing dates, and where the two can be told apart, the pre-season opening versus the full one. That mostly means trolling their Facebook feeds by hand. Sometimes the websites have it. Minnesota shows what a region looks like once it is filled in.
17 resorts in this region, none with dates on file yet. From the Midwest Ski Resort Guide by Midwest Skiers.
If you know Michigan · Upper Peninsula resorts, or want to take on the whole state, that is the whole job. Email eazydp@gmail.com. Dates for resorts already listed are just as welcome.