Dear Tom,

I like to swim in the lake when the temperature is warmest. Does the way from which the wind blows affect the water temperature in Lake Michigan?

Thanks, Danny Romano Chicago

Dear Danny,

Absolutely! Wind direction is a significant factor for the Lake Michigan water temperature. The sun’s rays warm the water closest to the lake’s surface while the deeper water remains quite chilly. When winds blow on-shore, the warm surface water is pushed toward the beaches, creating ideal swimming conditions. However, when winds blow offshore, a process called upwelling carries the warm surface water out into the lake, allowing the colder bottom water to replace it at the shore. In summer, Chicago beach water temperatures can drop dramatically with brisk west winds, while east winds bring the warm water to Chicago and chilly water to the Michigan beaches.