Hurricane Wilma could cost insurers up to $10bn, catastrophe modelling firm Risk Management Solutions predicted.
Wilma hit south west Florida as a category 3 storm packing maximum sustained winds of 125mph on Monday morning.
It was much weaker than Hurricane Katrina, which ravaged the Gulf Coast in late August, and was also moving much quicker, limiting its damage potential.
Other estimates have put the insured loss at only $2bn.
Meanwhile, AM Best has downgraded the financial strength rating of Montpelier Reinsurance to A- (excellent) from A (excellent) and the issuer credit rating to "a-" from "a".
AM Best said the downgrades were attributable to deterioration in Montpelier's risk-adjusted capitalisation after losses incurred from hurricanes Katrina and Rita,
The reinsurer had estimated losses of up to $675m from Katrina.