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A Hazard That Should Not be Overlooked

Tom Jeffery    |    Natural Hazard Risk

One billion dollars: the amount of damage caused by hailstorms on an annual basis in the United States, yet this particular hazard is often overlooked.1 Hail is produced by convective storms, which are associated with a number of hazards, including tornadoes, flooding due to excessive rainfall and strong straight-line winds. All of these events can cause damage to property, so the actual impact of a hailstorm can be easy to miss. Though flooding and tornado events tend to receive the most media attention, hail damage continues to represent sizeable material losses each year. Recent storms in South Dakota, Missouri and Texas are a reminder of the destruction hail can cause – and why we should be paying better attention to the risk.

Central and Southern Plains states tend to have the highest accumulation of hail damage each year, but virtually any location in the contiguous U.S. can experience convective storm formation. Not all hailstorms will cause significant property damage since the size of individual hailstones can vary, but larger hailstones can destroy the roof, siding and windows of a home, as well as the exterior of a vehicle.

The largest hailstone on record fell during a storm over Vivian, South Dakota in 2010.2 It measured nearly eight inches in diameter and weighed almost two pounds. While hailstones approaching that size are very rare, it only takes a diameter of approximately one inch for a hailstone to cause damage. In 2012, a series of storms resulted in a large number of hail-damaged properties. In April, storms swept through St. Louis, Missouri and caused an estimated $1.6 billion in damage.3 Then, just two months later, the Dallas-Fort Worth metro was hit by large hail that caused an estimated $900 million in damage.4

Earlier this year, Denton, Texas, located just north of Dallas-Fort Worth, experienced damaging hail that ultimately resulted in an estimated $500 million in damage. On April 3, a convective storm generated high winds and hail that ranged in size from penny to baseball diameters. Approximately 35,000 automobiles and 22,000 homes were damaged from the hail that fell during the storm. A CoreLogic study of the storm revealed that nearly half (47 percent) of the homes in the area impacted were affected by hail that was smaller than one-and-a-half inches in diameter. Of the remaining homes, 37.3 percent were in an area which was hit by hail between one-and-a-half and two inches in size, and more than 9,000 were struck by hail that was larger than two inches in diameter, for a total of 57,522 homes impacted.

From a property insurance perspective, it’s important to evaluate the risk and damage associated with hail in two ways—with the first being the analysis of hail risk. This is based on identifying the locations that are more susceptible to hail formation. While atmospheric conditions are constantly in flux and difficult to forecast, constructing an accurate hail risk analysis is possible using various tools, one of which provides a 10x10 km grid based assessment of damaging hail probability.

Another method of hail analysis, and one that is even more important for the insurance industry, is hail verification after an event has taken place. This analysis provides the ability to determine the location and size of hail impacts after the storm. It combines proprietary hail size algorithms, remote sensing and point-specific weather data to objectively determine what hail size affected each individual property parcel. Combining highly granular property parcel locations with not only the storm footprint, but also hail diameters, provides the key ingredients to help insurers understand where the damage occurred, and provides the ability to tabulate the properties affected.

With a better understanding of risk to each home in a geographic area, insurers can make better decisions about resource allocation, and more importantly, assist homeowners quickly and efficiently when disaster strikes. The damage from hailstorms may not be as visually shocking as other types of hazards, nor are they as likely to cause injury or death. But unlike Chicken Little’s infamous unfounded warning that the “sky is falling,” hailstones falling from the sky can cause significant damage and quickly escalate into the hundreds of millions of dollars for even a single event.


  • [1] National Oceanic and Atmospheric Administration, 2014.
  • [2] Monstrous hail Now the New National Record,, 2010.
  • [3] The Great St. Louis Metropolitan Hail Storms, NOAA, 2012.
  • [4] June 13th 2012 Severe Storms, NOAA, 2012.
  • [5] Massive Hail Pounds Texas, Arkansas, Causes Millions in Property Damages. The Weather Channel, April 11, 2014.

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