How often does Lake Michigan completely freeze over in the winter?
Shirley Melvis, Waukegan
In records dating from the middle 1800s, Lake Michigan has never completely frozen over, even in the harshest winters. It has been as much as 90 percent or more ice-covered (in 1903-04, 1976-77, 1978-79, 1998-99 and 2013-14), but the lake is an impressively huge reservoir of heat that is released only slowly into the atmosphere. In addition, constant wind and wave action further inhibits the formation of ice. In an average winter a little less than half the lake freezes over. The lake extends more than 300 miles north to south, and most of the open water is in the south part of the lake where the chill is less severe. Lake Erie, the shallowest of the Great lakes, is the only one that freezes completely over with any regularity in severely cold winters.