History of Hail in Timeline

Hail is solid precipitation consisting of ice balls or irregular lumps called hailstones, distinct from ice pellets. Hail forms through different processes than ice pellets. While ice pellets typically occur in cold weather, hail formation is hindered by low surface temperatures.

1965: Start of Hail Suppression Programs

Beginning in 1965, various countries initiated hail suppression programs to mitigate the threat of hail storms.

2005: End of Hail Suppression Programs Era

By 2005, 15 countries had undertaken hail suppression programs since 1965. These programs involved cloud seeding techniques to reduce crop damage from hail storms.

January 2010: US National Weather Service Hail Threshold Increase

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

July 29, 2010: Hail Accumulation in Boulder County, Colorado

On July 29, 2010, a stationary thunderstorm resulted in a foot of hail accumulation in Boulder County, Colorado.

June 5, 2015: Heavy Hailfall in Denver, Colorado

On June 5, 2015, hail up to four feet deep fell on one city block in Denver, Colorado, accompanied by rain and high winds. The hailstones, described as between the size of bumble bees and ping pong balls, fell for one and a half hours between 10:00 pm and 11:30 pm. Tractors were needed to clear the area, filling more than 30 dump truck loads of hail.

2023: Hailstorm Damage Costs in the United States

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, scientists in the United States will begin ICECHIP, a large-scale field campaign to study hail processes in thunderstorms across the Great Plains and the Colorado/Wyoming Front Range. The 2025 project involves 100 scientists from multiple countries and states.