(Bloomberg) -- The wildfires that raged across NorthernCalifornia last month will cost insurers more than $1.1 billion,according to catastrophe modeler Impact Forecasting.

The Valley Fire, northwest of San Francisco, destroyed almost2,000 homes, leading to at least $925 million in expenses for theindustry and making it the third-most expensive in Californiahistory, according to a report Thursday from Impact. The sum forthe Butte Fire, southeast of Sacramento, is more than $225million.

“The severity of the September wildfires in California serves asa reminder of how costly the peril can be for the insuranceindustry,” Adam Podlaha, head of Impact Forecasting, said in astatement.

Total economic losses, which include costs not borne byinsurers, will probably exceed $2 billion, helping to make 2015 thecostliest year for wildfires in the U.S. since 2007, according toImpact, which is a unit of London-based insurance broker Aon Plc.That was the year when the Witch Fire struck California’s San DiegoCounty.

Dry weather, high temperatures and gusty winds hampered effortsto contain the fires, resulting in at least six deaths. Throughoutthe U.S., wildfires burned more than 9 million acres (3.6 millionhectares) this year through Sept. 29, more than triple the total inthe same period of 2014, according to the National Interagency FireCenter.

Arkansas, Idaho and Oregon are among other states currentlyreporting fires, according to the center. Before this year, eightof the 10 costliest U.S. wildfires occurred in California,according to Property Claim Services data compiled by the InsuranceInformation Institute.

And, as Podlaha said in the statement, “the peak of theCalifornia wildfire season is just beginning.”

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