Hail size reports, hail swaths, and severe hail warnings worldwide
This hailstorm monitor tracks severe hail events globally, showing peak hail sizes and damage reports from active storms. Users searching for hailstorm near me, large hail report, or hail map can see current storm cells producing damaging hail and active warnings.
Hail forms inside thunderstorm updrafts strong enough to suspend ice particles in the supercooled portion of the cloud. Cloud droplets freeze on contact with the growing hailstone, building up alternating clear and opaque layers as the stone cycles through different parts of the storm. The strongest updrafts produce the largest hail — sustained updrafts above 145 km/h are required for golf-ball size hail, and supercell updrafts above 160 km/h can suspend baseball-size or larger hailstones.
Hail size is reported by comparison to familiar objects: pea (0.6 cm), penny (1.9 cm), quarter (2.5 cm — severe threshold), golf ball (4.4 cm), tennis ball (6.4 cm), baseball (7 cm), softball (10 cm), and grapefruit (12.5 cm or more). The largest authenticated hailstone in the US fell at Vivian, South Dakota in 2010 at 20 cm diameter, weighing 879 grams. Hail terminal velocity scales with size — large hail falls at over 160 km/h.
Severe hail causes billions in damage annually worldwide. Crops can be totally destroyed by even moderate hail. Vehicle damage requires golf-ball size or larger hail in most cases. Roof and exterior building damage scales rapidly with hail size and accumulation. The May 2024 Houston, Texas hailstorm and the 2017 Colorado hailstorm both produced over a billion dollars in insured damage in single events.
The eastern slope of the Rocky Mountains — particularly Colorado, Nebraska, Wyoming, and parts of Texas and Oklahoma — experiences the highest hail frequency in the United States, often called Hail Alley. Mendoza Province in Argentina is one of the hailiest places on Earth, with hail damage threatening the region's vineyards. India's hail belt across the northern plains and Bangladesh produces some of the largest documented hailstones globally.
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