U.S. property-casualty insurers will likely pay around $11.5 billion to homeowners and businesses due to third-quarter property losses from catastrophes, ISO's Property Claim Services Unit (PCS) said. In total, the catastrophes generated 1.7 million claims, PCS estimated.

The quarter saw a total of 11 catastrophes affecting 22 states, PCS said. The $11.5 billion represents the fourth-largest insured property loss in a third quarter since 1998.

The figure does not come close to the $48.4 billion in similar losses for 2005, and is also well behind the $23.7 billion from 2004, but the 11-catastrophe total tops both of those years, and every other year going back to 1998, in terms of frequency, according to PCS numbers.

Of the 11 catastrophes, PCS said six were caused by severe weather, such as wind, hail, tornadoes and flooding, while tropical storm systems were responsible for the other five catastrophes.

The 22 affected states ranged from New Mexico to North Dakota to Virginia, PCS said. Texas, Louisiana, Ohio, Kentucky and Illinois experienced the greatest losses.

Texas was hit the hardest with an estimated $6.4 billion in property losses.

"Although the current estimates of insured property damage are not record-setting, the frequency of events continues a trend that has occurred all year: a high number of events coupled with significant insured losses," Gary Kerney, assistant vice president, PCS, said in a statement.

He added, "These figures show that tropical systems can reach well inland and inflict extensive property damage--a fact that is often overlooked."

PCS declared 36 catastrophes though the first three quarters of 2008, totaling an estimated $22.1 billion of insured property damage and approximately 3.7 million claims.

Of those claims, PCS said approximately 2.5 million personal lines claims accounted for $14.5 billion of property damage, while 356,000 commercial lines claims cost an estimated $5.4 billion and 840,000 vehicle claims cost insurers $2.2 billion.