The pic. above is the thermometer taking the water temperature of Lake Michigan at Holland (MI) State Park Tue. morning. It was a bone-chilling 50 degrees! We had a classic case of upwelling late last week. The water temperature at Grand Haven State Park fell 25° in 24 hours!

Upwelling occurs when an offshore wind (an east wind here in West Michigan) pushes the warm surface water out toward the middle of the lake. Colder water from below the surface rises to take it’s place. When the wind changes direction and becomes onshore from the west or southwest, then the warmer water toward the middle of the lake will move back toward the Michigan shore.
Midday Tuesday Surface Weather Map

Here’s a midday surface weather map. Temperature is the number in red in the upper left of each station plot. The plots show a general northeast offshore wind and that trend should continue tomorrow.

Holland State Park – 11:30 am Thursday, August 18

Here’s a screen grab from the webcam at Holland State Park late Thu. AM. Note that while a few people are getting their toes wet, no one is swimming around in that cold water. Also, note the flag color is yellow. That’s not because of the waves. They want you to be cautious because of the cold water temperatures. With a light northeast wind, the lake is pretty calm. The Port Sheldon Buoy shows a wave height of just 5″ and a north wind at just 4 mph. At the mid-Lake Michigan buoy, the waves are 8 inches and the water temperature is 71.

Here’s more water temperatures this Thursday 8/18: Muskegon 60°, Grand Haven 55°, Holland 52°, Saugatuck 58°. Inland lakes are much water. The late Thu. water temp. at Reeds Lake in East Gr. Rapids is 77°

ALSO: This made me chuckle.

Have a great day – and thanks for reading my blog!