Ice dunes look like mounds of ice that form along the shoreline of a lake or ocean when conditions are just right. They form in very cold temperatures, when the air temperature is below freezing and the water temperature is just above freezing. As small ice chunks in the water and wave spray (which is smaller water droplets that come off the waves as they crash) crash along the shore, the ice accumulates onshore, creating these ice dunes.

You can see from this photo taken in Erie, Pennsylvania, ice dunes that formed along Lake Eerie. Wave action, beach topography, weather and the tidal range all can affect how dunes form and how large they become. Ice dunes can form as high as 15 feet or more.

While the ice dunes can be beautiful and attract a lot of attention, they can also be dangerous. While they form on land, many of them extend out over the water. Therefore, someone could easily fall through an ice dune into the near freezing water below. Ice dunes are mostly hollow as they are filled with mainly air pockets and have many cracks, therefore they aren’t as sturdy as they may seem. If you happen to fall through an ice dune, it can be difficult to get out and you might get trapped. It’s best to enjoy ice dunes from a distance!

Weather in your inbox

Forecast Location

Sign Up

By signing up you agree to the Terms & Privacy Policy. Unsubscribe at any time.

This segment originally appeared in today's edition of the Morning Brief newsletter. Sign up here to get weekday updates from The Weather Channel and our meteorologists.

J​ennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.