Water temperature image from Coast Watch, Michigan Sea Grant

As the air temperatures continue to become more mild with fall approaching, the Great Lakes surface water temperatures are reaching their peak.

As of Tuesday, the average surface temperature of Lake Michigan from Chicago to Mackinaw City was 62.9 degrees. On the same day, in 2016, the average temperature was 64.6, while two years ago the temperature was 59.2, according to Mark Breederland, an educator with the Michigan Sea Grant Extension in Northwest Michigan.

The data is collected using different methods such as off-shore buoys, like the one located in Little Traverse Bay outside of Petoskey, and information gathered from National Weather Service satellites.

“Those (the buoys) are our best data points, they get accurate surface temperatures all the time. From a satellite, they can actually get an average surface temperature in a one-kilometer-square grid, it’s a data point they average for the temperature,” Breederland said.

Although water levels are 18 inches above the long-term average, the surface temperatures are hitting their peaks throughout the Great Lakes.

“There is still great swimming weather going into September with some of our best temperatures,” Breederland said.

With Lake Superior being the farthest north, the biggest and deepest of the Great Lakes, it usually takes the longest time to reach peak temperatures. As a result, the surface temperatures reach their highest in September, according to Breederland. Lake Michigan usually hits its peak around mid- to late August, and remains warmer along the coastline.