When does Lake Michigan’s temperature peak in the summer? When is it the coldest in the winter?
Rebounding from icy 32 degree values in late winter, August is usually the month when the Lake Michigan water temperature reaches its highest level here. Readings usually top out in the upper 70s, but can reach the lower 80s in the warmest summers. Chicago-area shore water temperatures are taken at a depth of about 15 feet at the James W. Jardine Water Purification Plant near Navy Pier. The National Oceanic and Atmospheric Administration also maintains a permanent moored buoy in Lake Michigan about 50 miles east-southeast of Milwaukee that has been archiving the lake water temperature since 1981. The highest reading recorded there was 81.3 degrees on Aug. 18, 1995.