The Great Lakes have been slow to freeze this year, compared to years past. Currently, around 2.4% of the Great Lakes are covered by ice, concentrated in the Green Bay region off Lake Michigan and Saginaw Bay in Lake Huron. That's lower than 11% cover at this time last year.
Jia Wang is an ice climatologist for NOAA. He says it's been a warm winter in the Great Lakes region.
"[Ice cover] is very very low, unusually low this year, compared to other years and compared to the average. This year, air temperatures are so warm. Air temperature has a negative correlation with ice cover. Of course, if it's warmer, there's less ice cover," he says.