Lake Michigan has been warmer than average throughout 2016, according to the NOAA Coastwatch site.
Here are what the current surface water temperatures look like across the Great Lakes. Temperatures on the southern end of Lake Michigan are in the 70s and in the low 70s or upper 60s in much of the rest of the lake. There are some spots along the Wisconsin shore that are in the low 60s and 50s.
Here are the Lake Michigan average surface temperatures (blue) compared to 2016 (red). Lake temperatures have been running above average throughout the year. Air temperatures across the Great Lakes region have been running between 1 and 3 degrees warmer than the 1981-2010 average for 2016 as well (bottom map).