Under the formula, insurers would need to charge between $101 and $900 a year in premium to recoup losses from a hurricane on a two-story single-family home of 2,000 square feet built in 1980 with a 2 percent deductible and $200,000 worth of coverage on the structure.

Explaining the way models work, Mr. DeMartini said what modelers do is calculate the average loss estimate in a given area.

For New York City, ranging from Staten Island to the northern reaches of the Bronx, the premium on the same structure could range from $48 in the Bronx to $193 along the barrier island of Queens.

The model is based primarily on the 1938 hurricane, known as the Long Island express, that inflicted massive damage on Long Island, sending beachside mansions into the sea.

If there is any good news, said Mr. DeMartini, it is that this past year with no hurricane losses has given some relief to the markets and opened capacity.

One example he gave was of a $250 million cover with northeast exposure that received 12 reinsurance quotes at the end of 2006. The quotes were for premium increases ranging from 25 percent to nearly 93 percent. He said all 12 finally came in with a quote that raised the premium 15.5 percent.

“They had capacity,” he said. “They had no losses, and they had to put their capital to work.”