Average daytime high temperatures range from 60 degrees Fahrenheit in May, to the upper 80s in mid-summer, to the mid-60s in September. Average lows vary from 40 degrees in May, to the upper 50s in mid-summer, to 50 degrees in September. Average water temperatures in May and June are only in the 40s. Even in late summer, surface temperatures rarely exceed 60 degrees, except in protected bays. Average summer winds blow at from 5 to 20 knots with waves of from one to four feet. Winds of 30 to 40 knots and 6 to 12 foot seas are possible.
Check for an up-to-date weather on Lake Superior
Near Shore Marine Weather Forecast, within 5 miles of shore
Offshore Marine Weather Forecast, beyond 5 miles from shore
Weather Station - Devils Island, WI, located on the Devils Island Lighthouse
West Lake Superior Bouy, located 48 nautical miles North of Ironwood, Michigan
Did You Know?
In his “Report on Apostle Islands National Park Project, January 20, 1931”, landscape architect Harlan Kelsey noted that “the hand of man has mercilessly destroyed the islands’ virgin beauty, and, therefore, a largely controlling element as outstanding national park material even if other reasons made them eligible…this project does not meet National Park Service standards.”