Why Does Hail Happen?

It’s not just raindrops that fall during thunderstorms. Sometimes ice falls too. The ice is called hail, and it can form even during the warmth of summer. High up in a storm cloud, it’s so cold that small pieces of ice can form. The winds within the storm cloud can cause the ice to swirl around. When it bumps into cold water droplets, the water freezes onto the ice, making hail grow larger. Eventually, the hail is so big and heavy that it falls to the ground. 

Hail can be the size of peas. Large hail can be the size of a grapefruit and destructive. It’s heavy enough to dent cars and break windshields when it falls.

Small hail falling from the sky and onto a street with a car in the lower right on the photo

Sometimes hail falls during a thunderstorm—these little balls of ice form in the storm clouds where the temperature is freezing cold. 

Dirk Haun/ CC BY 2.0

Hundreds of tiny hailstones in a pile

Sometimes hail is tiny, and there is so much of it that it collects like the ground like snow. Each piece of hail is a little ball of ice.

Michael Pereckas/ CC BY 2.0

One large hailstone with a ruler next to it. The hailstone is more than 4 centimeters across.

This large hailstone is bigger than a ping pong ball. Hail this size can cause lots of damage when it falls from the sky.