Hailstorms
Hailstorms form inside strong thunderstorms when updrafts lift water into freezing air, building ice stones that can damage crops, roofs, vehicles, and people.
What hailstorms are
A hailstorm is a thunderstorm that produces hailstones: balls or irregular chunks of ice that fall from convective clouds. Hail can be small and brief, or it can become large enough to damage property and crops. The strongest hailstorms usually come from severe thunderstorms with intense updrafts.
How hailstones grow
Hail begins when water droplets or small ice particles are lifted into very cold parts of a thunderstorm. Supercooled droplets freeze onto the growing stone. If the updraft is strong enough, the hailstone can remain suspended or be lifted repeatedly, collecting more layers before it finally becomes too heavy and falls.
Layers of ice
Many hailstones show alternating clear and cloudy layers. These layers can form as the stone passes through parts of the storm with different liquid water content and temperature. Clear ice often forms when water freezes more slowly, while cloudy ice can trap air bubbles as droplets freeze quickly.
Why supercells make large hail
Supercell thunderstorms can produce especially large hail because they have strong, persistent, rotating updrafts. Those updrafts can hold hailstones aloft longer than ordinary storms, giving them time to grow. Wind shear, instability, moisture, and freezing-level height all influence hail size.
Radar and forecasting
Meteorologists use radar, satellite data, storm reports, sounding data, and high-resolution models to assess hail risk. Dual-polarization radar can help identify hail within a storm by showing information about particle shape and size. Forecasting exact hail size at one location remains difficult because storm structure changes quickly.
Damage and safety
Large hail can fall at dangerous speeds. During a severe thunderstorm warning, people should move indoors and away from windows. Vehicles, skylights, greenhouses, solar panels, livestock, and crops are especially exposed. After a storm, broken glass, damaged roofs, and flooded streets can add secondary hazards.
Climate and hail risk
Hail risk depends on a mix of storm instability, moisture, wind shear, and freezing levels. Climate change may alter those ingredients in different ways by region. Warmer air can support stronger storms, but higher freezing levels can also change how hail grows or melts before reaching the ground.
Why they matter
Hailstorms are often less famous than tornadoes or hurricanes, but they cause major economic losses. They matter to agriculture, insurance, roofing, transportation, power systems, outdoor events, and public safety. Understanding hail helps people take severe thunderstorm warnings seriously even when a tornado is not expected.