History of Hail in Timeline

Hail is a form of solid precipitation consisting of hailstones, which are balls or irregular lumps of ice. It is often confused with ice pellets, but they are different. Ice pellets typically fall in cold weather, while hail formation is inhibited by low surface temperatures.

1965: Hail suppression programs undertaken by 15 countries

From 1965, hail suppression programs have been undertaken by 15 countries.

2005: Hail suppression programs undertaken by 15 countries

Until 2005, hail suppression programs have been undertaken by 15 countries.

January 2010: US National Weather Service hail diameter threshold increase

In January 2010, the US National Weather Service increased its hail diameter threshold to 1 inch (2.5 cm), up from the previous threshold of 0.75 inches (1.9 cm).

July 29, 2010: Foot of hail accumulates in Boulder County, Colorado

On July 29, 2010, a thunderstorm that was nearly stationary caused a foot of hail to accumulate in Boulder County, Colorado.

June 5, 2015: Four feet of hail falls in Denver, Colorado

On June 5, 2015, hail up to four feet deep fell on one city block in Denver, Colorado. The hailstones were described as between the size of bumble bees and ping pong balls.

2023: Hailstorms cost the United States $46 billion in damage

In 2023, hailstorms in the United States caused $46 billion in damage to cars, roofs, and crops, according to the Insurance Institute for Business & Home Safety (IBHS).

2025: ICECHIP field study begins

In Spring 2025, the "In-situ Collaborative Experiment for Collection of Hail In the Plains" (ICECHIP), the world's largest field campaign devoted to studying hail, began in the United States. The project involves 100 scientists and aims to study hail processes in thunderstorms.