Catastrophes cost the U.S. property/casualty insurance industry an estimated $38.6 billion in losses during the first nine months of the year, said a report by A.M. Best Co. Inc.

That is an increase of 140% from the amount of catastrophe losses suffered by U.S. insurers during the same period in 2010, according to the rating agency. This year’s nine-month estimated total is nearly double the $19.6 billion in catastrophe losses sustained by U.S. insurers during all of last year.

Best said the “vast majority” of the losses were associated with tornadoes and hailstorms that struck the Midwest and Southeast during the spring, as well as Hurricane Irene in September and blizzards in the Midwest.

In addition, some U.S. insurers suffered losses in catastrophes outside the United States, including the March earthquake and tsunami in Japan.