Isaac, the storm drenching drenching Arkansas and Louisiana, may cost insurers as much as $2 billion in the U.S., risk-modeling firm AIR Worldwide said.

Bloomberg reports that the industry’s claims costs, including wind and storm-surge damage to residential, commercial and industrial onshore properties, will be at least $700 million, according to AIR. The Boston-based firm’s prediction today follows rival Eqecat Inc.’s  Aug. 29 estimate of insured losses from Isaac of between $500 million and $1.5 billion for onshore property.

By comparison, the estimates are a fraction of the $41.1 billion cost for Hurricane Katrina, the 2005 storm that struck Louisiana and caused flooding in New Orleans. Last year, Hurricane Irene cost $4.3 billion in claims along the East Coast.

Offshore oil rigs and gas platforms in the Gulf of Mexico probably didn’t suffer “significant physical damage” from Isaac, AIR said. Claims also may be lower from the energy industry because insurers are selling less business-interruption coverage after losses from Katrina.

The industry is able to withstand claims from Isaac, even though most losses will be borne by primary carriers rather than reinsurers, Fitch Ratings said in a note on Aug. 28, the day the storm made landfall.

Allstate Corp., the largest publicly traded U.S. home and auto insurer, advanced 0.9 percent to $37.50 at 9:40 a.m. in New York. Warren, New Jersey-based Chubb Corp. climbed 0.8 percent to $74.07 and Travelers Cos. Inc. gained 1.2 percent.