We're Coming Up on the Peak of Activity in Hail Alley

Severe hail causes an average of $1.42 billion in property and crop damage in the United States each year, using data from 2005 through 2015. This is the hail that smashes your windshield, takes the siding off your house and causes roof damage to businesses. 

Much of this damage occurs during the spring and summer months as warmth and humidity build, fueling severe thunderstorms. A large portion of hail-producing thunderstorms occur in the Plains states, according to a study lead by John L. Cintineo et al. 

(MORE: Marble Sized Hail: Our Two Cents)

Severe hail occurs most often in a triangular region from west Texas to northwest Missouri to the western Dakotas.

In the study, the authors defined severe hail as hail that's at least 0.75 inches in diameter, or about the size of a penny. Much of this region averaged at least 0.5 days of severe hail from 2007 to 2010. These same areas have one day, on average, per year when hail of any size reaches the ground.

Texas, Kansas, Oklahoma and Nebraska average the most days with damaging hail larger than golfball size. Most of the hail in Texas and Oklahoma occurs in the western portions of those states.

A few eastern hotspots for hail are around the Potomac and the Chesapeake bays in the mid-Atlantic and the coasts of Georgia and South Carolina, according to the study.

(MORE: How Hail Forms and Why It's a Threat)

Thunderstorms capable of producing severe hail migrate northward through the spring and summer as favorable conditions intensify and spread from the Gulf of Mexico to the Canadian border.

The Southeast gets battered most often by hail in May, but the peak hail numbers on a national scale occur in June, when thunderstorms are producing the most severe hail in the Plains, according to the study. 

Hail becomes most frequent toward late summer farther north into the northern Plains.

The hail threat diminishes rapidly from September to October. Severe hailstorms tend to hibernate for the last two months of the year as cooler and drier winds bring winter.

This climatology study looked at immense amounts of national radar data to diagnose if thunderstorms likely produced hail, and if so, how big the hailstones were able to grow. This was done by using multi-radar multisensor severe weather guidance from radar data and local models to build an unbiased history of hail throughout the year and the country.

Past studies that used storm reports from the Storm Prediction Center relied on the public's submission of reports to National Weather Service offices. One big flaw in this procedure is that it relies on population density, and therefore, more sparsely populated areas will have fewer reports.

(MORE: Large Hail: An Underrated Danger)

The use of radar data patches holes where people do not live and creates a more trustworthy map of where hail falls.

The study did compare their results to previous studies that used storm reports as the primary dataset and found similar results with the most severe hail days occurring in the central Plains and a secondary bull's-eye in the western Carolinas. This secondary bull's-eye may be due to a higher population that reports severe storms more often along the East Coast.