Mr. Hamid led the development of the Florida Public Hurricane Loss Model, which is used by state regulators to assess insurers’ financial strength, among other things. But he said it was impossible to predict which insurers might be vulnerable, because the companies’ exposures vary by region and the terms of their reinsurance contracts are not known.

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 in 1992.

Until now, Andrew was ranked as Florida’s most destructive storm, causing $27 billion in damage — $47 billion in today’s dollars. Twenty-two insurers failed, 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 that represent 60 percent of the state’s homeowners’ insurance market — suggested that Irma could be more significant because it would cause such a wide swath of damage.

“It’s the first time in history that every county in Florida was on hurricane watch,” he said.

Using the same benchmark as Mr. Hamid, Mr. Petrelli said he believed his Florida client insurers could withstand a storm like Hurricane Andrew, mainly because they currently hold more reinsurance than ever. He said he could not speak for the other insurers because he does not rate them.

Reinsurance allows companies to transfer some of their exposure to other, well-capitalized companies, adding capacity but reducing their profits. Mr. Petrelli said that was why the national insurers pulled back from Florida — their reinsurance needs in other states were far less expensive and did not undermine profits.

“We make them buy more reinsurance every year,” he said of his Florida clients, “because the value of homes goes up every year, the number of homes goes up every year, and the cost of repairs goes up every year.” For the last few years, reinsurance prices had fallen, even for companies in high-risk Florida, because the state has not had a major storm since 2005.