History of Hail in Timeline

Hail is a type of solid precipitation, distinct from ice pellets, consisting of ice balls or irregular lumps called hailstones. Unlike ice pellets, hail formation is hindered by low surface temperatures. These differences highlight the unique conditions and processes that lead to the development of hail, making it a distinct weather phenomenon.

1965: Hail Suppression Programs Undertaken

Starting in 1965, hail suppression programs were undertaken by 15 countries. These programs aimed to reduce hail damage, particularly to crops.

2005: Ongoing Hail Suppression Programs

By 2005, hail suppression programs had been undertaken by 15 countries since 1965. These programs were attempts to reduce hail damage, particularly to crops.

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), an increase from the previous threshold of 0.75 inches (1.9 cm).

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

On July 29, 2010, a stationary thunderstorm caused a foot of hail accumulation in Boulder County, Colorado, demonstrating the impact of localized, intense hailstorms in mountainous regions.

June 5, 2015: Extreme Hail Accumulation in Denver, Colorado

On June 5, 2015, Denver, Colorado experienced extreme hail accumulation, with hail up to four feet deep falling on one city block. The hailstones, described as between the size of bumble bees and ping pong balls, were accompanied by rain and high winds. Tractors used to clear the area filled more than 30 dump truck loads of hail.