On Tuesday, The Watershed Center said Grand Traverse Bay was officially frozen. The official designation happens after West Bay is frozen from Traverse City to Power Island for more than 24 hours. Even though that's only a fraction of the bay, that's been the official measurement for over a hundred years.
Heather Smith, Grand Traverse Baykeeper at The Watershed Center, says the bay didn’t freeze over the last two winters – not since 2015. She says, since 1990, it has only frozen between 20 to 30 percent of the time.
"We’ve historically seen higher percentages of freeze years," Smith says, "which is an indication that our long-term climate trends may be changing."
Smith says there is still open water north of Power Island.
"We do know that Suttons Bay is frozen, and there is certainly some ice coverage up near Northport," she says, "but certainly not frozen all the way across."
Smith says ice may not be thick in a number of areas and people venturing out onto it should be very careful.
The National Oceanic and Atmospheric Administration says over two-thirds of the Great Lakes are covered in ice. Half of Lake Michigan is covered. There’s ice on 80 percent of Lake Huron, Superior has 77 percent coverage, Lake Erie is almost entirely covered in ice at 91 percent. There's not much ice on Ontario – just 15 percent.