Lake Michigan is 10-25 degrees colder than normal this summer. Here's why...

Good practical stuff. Upvoted!

The article offers a few explanations for why the Lake is significantly colder this summer than most. Here's the most succinct:

This explanation is in line with weatherman Tom Skilling's Chicago Tribune column: "Hot weather arrives in the city on brisk south and southwest winds that push the warm surface water out into the lake toward the east shore, allowing the colder bottom water to upwell and replace it."