Jeff Andersen, who doubles as a geography professor at Michigan State University, said the lakes were more than 88 percent covered with ice this week, which will keep the region chilled a little longer than usual.
"We haven't seen many winters like this that are cold from beginning to end," Andersen told the Detroit Free Press. "It has been an extraordinary winter, and the ice cover is a manifestation of that unusually cold winter."
The ice coverage was near -- but not likely to break -- the 1979 record of 95 percent coverage. Temperatures were expected to climb into the 40s next week.
The deep freeze and the icy lakes have minimized lake-effect snowfalls and will keep fruit trees dormant longer, which will minimize the likelihood of damage from a spring cold snap, Andersen said.
The ice also limits evaporation, which could raise the low water levels in the lake.