In fact, in late November of this year, an early arctic weather pattern turned the Midwest cold and windy - the perfect ingredients for iced lighthouses on the Great Lakes. When I arrived at the lighthouse, my expectations were correct. This was the earliest I can remember, where the outer lighthouse in St. Joseph, Michigan was completely covered in ice. As a rule, mid to late December is the typical time for icing -cold, windy, and the lake is still liquid. Any later, and Lake Michigan tends to freeze over, and the splashing and spray are suppressed, so the lighthouses don't ice up.