Rare November Storms Cost Tops $1 Billion: Aon

Tornadoes and thunderstorms that swept across the U.S. Midwest last month will probably cost more than $1 billion in economic losses, led by damage in Illinois and Indiana, according to insurance broker Aon Plc.

Insurers estimated losses in the hundreds of millions of dollars, the London-based broker said in a report today.

The severe weather Nov. 17 and Nov. 18 killed at least 10 people and injured 300 others, Aon said in the document. There were 74 confirmed tornadoes by the National Weather Service’s Storm Prediction Center last month, making it the third-most prolific November outbreak since 1950, according to the report.

“Dozens of tornadoes occurred and multiple communities were decimated” in Illinois and Indiana, Aon said. The twisters were part of “a rare November major severe weather outbreak.”

There were seven U.S. tornadoes last year in November, compared with 44 for the month in 2011 and 53 in 2010, according to the Storm Prediction Center. April, May and June are typically more common months for the storms, with the most vulnerable states including Texas, Oklahoma and Kansas in a region known as Tornado Alley.

State Farm Mutual Automobile Insurance Co. is the largest home insurer in Illinois, followed by Allstate Corp., according to 2012 data compiled by A.M. Best Co. Both insurers are based in the state, with Allstate in Northbrook and State Farm in Bloomington.

Super Typhoon Haiyan was the costliest natural disaster last month, with about $5.8 billion of economic losses, including damage and reconstruction costs. Insurers’ losses were probably in the hundreds of millions, according to Aon, which is the world’s second-largest broker by market value. The storm, which made landfall in the central Philippines, left 5,719 people dead and more than 1,700 missing, according to the report.

(With assistance from Brooke Sutherland in New York. Editors: Dan Kraut, Dan Reichl)