Hailstorms are frequent occurrences across the U.S. Most hailstorms occur during either the spring or fall months, are very localized events, and don't cause extensive property damage. However, occasionally hailstones can reach about 1.5 inches in diameter. When this occurs, they can cause significant property damage to cars, windows and siding. When hailstones reach three inches in diameter, they can cause major roof damage.