But, fortunately, some forecasters sharply rolled back their damage estimates late Sunday, as Irma moved up the Florida peninsula and lost strength.
“There may yet be a Florida insurance market on Tuesday,” said Charles C. Watson Jr. of Enki Holdings L.L.C., who had been projecting losses of $172 billion on Sunday morning but just $49 billion by evening.
Insurer strength could be more of an issue in Florida than in eastern Texas, where most of Hurricane Harvey’s damage was caused by inland flooding. Homeowners’ insurers do not generally provide flood insurance. In Florida, flooding was expected, too, but because of Hurricane Irma’s size and path, much of the destruction will be from high winds, a peril that is covered by standard homeowners’ policies.
Investors dumped the stocks of Florida insurers last week as they anticipated the resulting claims and losses. Not all the insurers are publicly traded, but the second largest in the Florida market, Universal Property & Casualty Insurance, saw the shares of its corporate parent, Universal Insurance Holdings, drop by 15 percent on Thursday.
Shares of two medium-size insurers, Heritage Property & Casualty Company and Federated National Holding Company, fell to 52-week lows on Friday. (The biggest, Citizens, is state-owned and does not issue shares of stock.)
Mr. Hamid said it was impossible to tell yet which insurers might be vulnerable, because the companies’ exposures vary by region and the terms of their reinsurance contracts are not known. He led the development of the Florida Public Hurricane Loss Model, which is used by state regulators to assess insurers’ financial strength, among other things.
Long before Hurricane Irma started bearing down, Mr. Hamid stress-tested the larger homeowners’ insurers in Florida and found that they would withstand a worst-case scenario, as he defined it at the time: a storm like Hurricane Andrew.
Until now, Andrew was ranked as Florida’s most destructive storm, causing $27 billion in damage — $47 billion in today’s dollars — when it struck in 1992. Twenty-two insurers went under, leaving a million policyholders without coverage.
Joseph L. Petrelli, president of Demotech, an Ohio-based company that reviews and rates regional and specialty insurers — including about 50 in Florida — suggested that Irma could be more significant because it would cause such a wide swath of damage.
“It’s about 350 miles…