U.S. storms are the costliest natural disasters this year

Thunderstorms sweep across the nation

American property owners and businesses are getting soaked by storms.

A series of hailstorms and tornadoes have caused total U.S. damages of $18.5 billion in the first six months of 2017, according to a new report from top insurer Munich Re. Three of the five costliest disasters in the first half of the year were due to U.S. thunderstorms, while the costliest event for insurers was a powerful thunderstorm that hit the U.S. in early May and caused overall losses of $2.2 billion and insured losses of $1.8 billion.

Losses suffered by American businesses and homeowners dominate the natural catastrophe statistics for the first half of the year, the report found. Nevertheless, worldwide losses from catastrophic events have declined, with total insured losses declining to $19.5 billion in 2017 from a decade-long average of $29 billion in losses during the first half of the year.

"During the first half of 2017, we continued to clearly see the impacts of tornado and hail events in the United States in terms of damage to homes and business, which ultimately result in direct and indirect losses to the economy," said Tony Kuczinski, president and CEO of Munich Reinsurance America, in a statement.

Dozen of tornadoes tear through the Midwest

The German company said overall losses, included those that weren't insured, totaled $41 billion — compared with last year's $111 billion and an average $102 billion.

Munich Re said the extreme U.S. storms are "presumed to have been at least partially influenced by a natural climate phenomenon, especially in the first quarter of 2017," including a phenomenon called "coastal El Niño," which can change the atmospheric circulation over the U.S. and increase the chances of severe thunderstorms.

Munich Re Board member Torsten Jeworrek added, "The exceptional accumulation of severe thunderstorms in the U.S.A. highlights just how important it is for insurers to have in-depth knowledge of natural catastrophes and how these are affected by climatic changes. This is true of both natural climatic changes and those that are man-made."