Hail is a form of solid rain consisting of balls or irregular lumps of ice, measuring between 5 millimetres or 15 centimetres in diameter. Hail formation requires strong, upward motion of air freezing temperatures at lower heights. Storms that produce hail that reaches the ground are known as hailstorms. Hailstorms normally last from a few minutes up to 15 minutes. Hail in the tropics occur mainly at higher elevations. It may be accompanied by other severe weather events, such as cyclones and tornadoes.
Hailstorms are a common, costly and potentially hazardous weather event that can cause injuries to people, and damage to buildings, vehicles and crops. Accumulating hail can cause loss of power and bring down trees. Hail damage to roofs may go unnoticed until leaks or cracks become obvious. Flash floods and mudslides within areas of steep terrain can be a concern with accumulating hail. Rarely, massive hailstones have been known to cause concussions or fatal head injuries.