Hail most often occurs in spring, summer, and fall. Hail develops when strong updrafts carry raindrops to the tops of clouds during thunderstorms. The rain particles form hailstones when they freeze in the cold air aloft; they grow larger as more rain droplets are uplifted. Hail falls to earth when the updraft is no longer able to support the weight of the particles.

The Great Plains states are especially prone to hailstorms produced by strong thunderstorms that form east of the Rocky Mountains. In 2016, the top five states with hail damage insurance claims were Texas, Colorado, Missouri, Illinois, and Nebraska.

In 1986, Jonathan Webb, a meteorologist at England’s Tornado and Storm Research Organization, introduced a hailstorm intensity scale. It ranks the size of hailstones and corresponding damage on a scale from 0 to 10.

Freezing rain is a winter event. It occurs when rain falls as liquid and then freezes on the ground or any surface that is at or below 32 degrees Fahrenheit. Rain that falls through a layer of cold air aloft becomes sleet. A half-inch of freezing rain can add as much as 500 pounds of weight to power lines and tree limbs.

On April 10, 2001, golf ball to baseball-sized hail swept through three states along the Interstate 70 corridor from west of Kansas City to near Effingham, Illinois. Hail damaged over 120,000 homes and over 65,000 vehicles. Total insurance claims amounted to near $2 billion. It was, at the time, the costliest hailstorm in U.S. history.

The largest hailstone on record fell near Vivian, South Dakota, on July 23, 2010. It measured seven inches in diameter and weighed nearly two pounds.