Georgian Bay is notorious for quick and sudden changes in weather, especially wind and storms, this could be an issue with 200x80km of open water to pick up speed, the waves can get astronomical.
Also have been water spouts, like tornadoes on water, have only heard of a few though and you can see them forming.
The islands along the eastern shore should provide some protection but have to now worry about the numerous shoals that lie just under the surface of the water.
Western shore has almost no protection.
Will need to be extra extra careful and mind the weather forecast religiously. On the Trent trip I usually listened in the morning and evening, will have to keep my VHF handy and monitor frequently.