What is fog and why is it so bad near Lake Michigan?

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Drone Pic By Steven Hutton - Milwaukee May 14, 2025

We've seen a lot of very thick fog recently. It rolls in like a slow-motion wet blanket or a thick pea-soup and seems to swallow up entire skylines. It can also make morning commutes feel like something out of a horror movie. But what is fog, really?

What is fog?

What we know:

Fog is essentially a cloud on the ground. It forms when the water vapor in the air cools and condenses into very tiny liquid droplets.

Fog forms when warm, moist air meets the cooler ground or cooler air, which is why fog is most common overnight and in the early morning.

The air is calm and stable. This allows the moisture in the air to build and settle on the ground.

Temperatures drop to the dew point, causing the air to saturate and condense into fog.

Why Is It Worse Near Lake Michigan?

Dig deeper:

Lake Michigan often plays the role of fog-maker-in-chief for Eastern Wisconsin. The lake’s cool water can dramatically lower nearby air temperatures, especially when warm, humid air blows in from the south or west. 

This quick cooling triggers condensation, forming advection fog, which is a particularly dense and persistent kind of fog.

Also, the lake’s massive surface can amplify wind shifts and temperature contrasts, making fog thicker and more widespread along the shoreline.

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Fog Safety 101

What you can do:

If you find yourself in foggy conditions:

• Slow down and use low-beam headlights only as high beams will just reflect off the fog and make things worse.
• Leave extra distance between you and the car ahead so you have more time to react.
• Use fog lights if your vehicle has them for better visibility.
• Avoid sudden stops and lane changes so other drivers aren't taken by surprise.
• Pay close attention to your speed as being in a fog reduces your sense of speed and can cause you to go too fast or too slow.
• If visibility is near zero, your safest move is to pull over somewhere secure and wait it out.

Drone Pic By Steven Hutton - Milwaukee May 14, 2025

Fog may look beautiful rolling over the lakefront, but don’t let it fool you—it's one of the most dangerous weather conditions for drivers. Stay cautious, stay visible, and when in doubt, take it slow.