Costliest hailstorm

The costliest hailstorm on record is the Tristate Hailstorm, which occurred in the central United States on 10 April 2001. The Tristate Hailstorm was a massive high-precipitation supercell that formed over eastern Kansas in the early afternoon, and dropped its first load of cherry-sized hailstones near Topeka, Kansas, at 2.30 p.m. Over the next eight hours, it travelled east passing over southern Kansas City into Missouri, then onward to St Louis and into southern Illinois. The storm spawned a few small tornadoes and caused some minor flooding, but it was the hail – which reached up to 7 cm (2.75 in) in diameter – that caused the vast majority of the damage. Hail-related insurance losses totalled $1.5 billion (equivalent to $2.1 billion in 2019) and the overall economic damage has been estimated to have been as much as $3 billion.

By unlucky chance, the path the storm took almost perfectly followed Interstate 70, one of the busiest east–west transport routes in the United States. It passed over several large towns as well as the city of Columbia, Missouri, before reaching the outskirts of St Louis. The storm approached the city from the north-west, passing over the Ford Motor Company assembly plant in Hazelwood (where hundreds of brand new cars were parked in outdoor lots), and Lambert International Airport (where it caused significant damage to 22 airliners).

In the aftermath of the storm, there were 65,000 insurance claims for automobile damage, 120,000 claims for residential property damage and 8,000 commercial business claims.