History of Hail in Timeline

Hail is a form of solid precipitation, consisting of ice balls or irregular lumps known as hailstones. It differs from ice pellets, though often mistaken for them. Hail formation is typically inhibited in cold weather conditions, unlike ice pellets which tend to fall in cold weather.

1965: Start of Hail suppression programs in various countries

From 1965, Hail suppression programs have been undertaken by 15 countries. These programs continued until 2005.

2005: End of Hail suppression programs in various countries

Hail suppression programs that had started in 1965 were undertaken by 15 countries until 2005.

January 2010: US National Weather Service hail diameter threshold increase

In January 2010, the US National Weather Service increased the 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 foot of hail accumulated in Boulder County, Colorado due to a stationary thunderstorm.

June 5, 2015: Hailstorm in Denver, Colorado

On June 5, 2015, a hailstorm dropped up to four feet of hail on one city block in Denver, Colorado. The hailstones, 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 removed over 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 project begins

In Spring 2025, the ICECHIP project (In-situ Collaborative Experiment for Collection of Hail In the Plains) will begin. This project will study hail processes in thunderstorms in the Great Plains and along Colorado and Wyoming's Front Range of the Rocky Mountains and involves 100 scientists from four countries and 11 states.