This winter has been one of extremes, from periods of above normal warmth to periods of extreme cold. The extreme cold has led to the Great Lakes being covered by a large percentage of ice. According to the Great Lakes Environmental Research Laboratory, ice coverage peaked at 92 percent across the collective Great Lakes.
With ice coverage being so high this past winter, we wanted to know the maximum ice coverage percentages of previous winters for the Great Lakes and for Lake Erie in particular.
According to data obtained from GLERL, from 1973 to 2011, the Great Lakes collectively had an average annual maximum ice coverage of 56 percent. During this period, the highest annual maximum ice percentage was recorded in 1979, where the ice coverage reached 94 percent. The lowest maximum was recorded in the winter of 2002 of only 9.5 percent.
For the same period of interest, Lake Erie had an average maximum ice coverage of 88 percent. The highest percentage, 100 percent, was recorded during the winters of 1978, 1979 and 1996. The lowest percentages were recorded during the winter of 1998, with an ice coverage percentage of 5.4 percent.
From Lake Erie's data in particular, it is clear that most winters a large percentage of Lake Erie freezes. This is more than likely connected to Lake Erie being one of the shallowest Great Lakes. Its maximum depth is 210 feet. Lake Michigan, on the other hand, has a maximum depth of 925 feet, and only has an average maximum ice coverage of 40.8 percent. The shallower the lake, the more annual ice coverage.