Severe thunderstorms and hail: Concentrated events that pack a punch

April 6, 2023 / 2 min read

Severe thunderstorms, which can bring damaging hail, are a common and destructive natural phenomenon in the United States, causing more than half of annual reported insured losses since 1985.¹ A large outbreak can cause $25 million or more in insured losses, but even a series of smaller events can have an aggregate effect on an insurer’s book.

severe-thunderstorms

A large outbreak can cause $25 million or more in insured losses, but even a series of smaller events can have an aggregate effect on an insurer’s book.

The most severe hail behavior over the past ten years occurred in 2016 and 2019. Activity in 2022 surpassed 2021, but it still fell short of the 10-year average of 5,086 hail events and was lower than 2019 and 2020 totals, according to the National Oceanographic and Atmospheric Administration (NOAA). Size and severity vary; as shown below, events generating 3,000 or more hail claims average 10 to 20 per year in the United States, as frequency of hail fluctuates up and down.

A new white paper discusses this peril in depth as part of a Verisk's natural hazard series, Ice, Fire, Wind, and Water.

Widespread damaging hail events have grown beyond the Midwest’s traditional “hail alley” to encroach on Eastern states and more populated areas. One storm in 2022 even brought an extremely rare hail event to the Los Angeles area.² The timing of hail outbreaks, historically concentrated in spring and summer, is also shifting: March and August activity declined significantly over the past ten years, but the season lingered into October in 2022.

A threat to more properties

At least one damaging hail event affected nearly 10 percent more U.S. properties in 2021 than in 2020, according to Verisk LOCATION data. This amounted to more than 6.8 million properties. Pennsylvania and Maryland joined the top ten ranking for hail-affected properties in 2021, marking an eastward migration of damaging events that has implications for insurers writing properties outside the traditional hail alley.

top-ten-states

The exposure up on the roof

Roofs bear most of hail’s destructive force, which can have cumulative effects over time. Understanding roof risk in a way that accounts for material, age, condition, and replacement costs is crucial for insurers exposed to this peril. In regions where hail or wind events are more frequent and severe, roof condition scores tend to be worst.

All of this matters because of the high cost to repair or replace roofs and the tendency for hail damage to go undetected for months or years, potentially making the eventual roof claim more severe. Roofing line items were included in 1.8 million residential claims and 41,000 commercial claims in 2022, making up around 38% of residential assignments and 31% of commercial assignments respectively.

The Verisk Severe Thunderstorm Model for the United States, Verisk, 2022, < https://www.air-worldwide.com/siteassets/Publications/Brochures/documents/us-severe-thunderstorm-brochure >, accessed on March 3, 2023.
Quinn Wilson, “Southern California gets rain, hail, lightning and ‘thundersnow’,” The Press-Enterprise, February 15, 2022, < https://www.pressenterprise.com/2022/02/15/southern-california-gets-rain-hail-lightning-and-thundersnow/ >, accessed on March 3, 2023.