Hail facts

Biggest hail stone: A hailstone measuring 8 inches in diameter and weighing 1.67 pounds, was found in Coffeyville, Kansas on 3rd September 1970.

The largest hailstone on record to fall in the United States was in Coffeyville on Sept. 3, 1970. It measured 7.5 inches in diameter and weighed 1.67 pounds.

Hailstones form in the updraft of a thunderstorm with stronger storms producing larger hail. The updrafts pull the precipitation up into the cloud, adding layer upon layer of moisture.

Cut in half, a hailstone has concentric rings like an onion, which reveals the number of times it traveled to the top of the storm before falling to Earth.

A thunderstorm is classified as severe when hailstones are three-fourths of an inch or larger and winds exceed 58 mph.

Hailstones can range from pea-sized (one-quarter inch) to golfball-sized (1.75 inches) to softball-sized (4.50 inches.)

While rarely a threat to physical safety, large hail results in nearly $1 billion a year in damage to property such as crops, roofs, automobiles and other outdoor objects.

When the hail falls to Earth, they come zipping down at 70 to 100 mph. That is why it is a good idea to stay indoors during a major hailstorm!

Source: FEMA, National Weather Service.

Hail Facts about Colorado

The hail season in Colorado is March through October.

June has the highest frequency statewide, averaging over 130 reported severe hailstorms a year.

The vast majority of hail occurs May through August.

Fort Collins has its most frequent hailstorms in May, but its largest hail comes in July and August.

Hail is primarily an afternoon or evening phenomenon in Colorado.

Most severe hailstorms occur between 1:00 p.m. and 9:00 p.m. MST.
Hailstorms rarely last more than 15 minutes at any given location.
The median duration is 6 minutes.

The storm itself may drop hail continuously for several hours along its path.

In Colorado, hail is a regional problem.
It rarely hails in the mountains or on the Western Slope.
Hail severity increases as you go east from the Front Range foothills toward the Kansas border.

Source - Nolan Doesken, Colorado Climate Center