Yes, it's true, Lake Superior can be really cold. The average annual water temperature of the lake is about 40 degrees Fahrenheit. On warm, calm, sunny summer days, however, water temperatures in the Apostle Islands' protected shallow bays can climb into the 70s. Some favorite swimming locations are Little Sand Bay and Meyers Beach on the mainland and Julian Bay on Stockton Island.
Last updated: April 10, 2015