WASHINGTON — Late mortgage payments climbed to a 2 1/2-year high in the final quarter of 2005 as Gulf Coast homeowners struggled with fallout from the hurricanes and lofty energy prices that, along with rising interest rates, squeezed the budgets of others across the country.

The Mortgage Bankers Association, in its quarterly mortgage survey, reported yesterday that for all loans tracked, the percentage of mortgage payments that were 30 or more days past due rose to 4.70 percent in the October-to-December quarter of last year.

That was up from the prior quarter's 4.44 percent delinquency rate and was the highest since the second quarter of 2003.

The association's survey covers 41.2 million loans.

One factor in the growth of late mortgage payments is the problems people faced in the communities devastated by last year's hurricanes, which have pushed up delinquency rates in Louisiana and Mississippi, the association said.

But other factors played a role.

"We have been expecting an uptick in delinquencies due to a number of factors: The seasoning of the loan portfolio, the increased share of the portfolio that are adjustable-rate mortgages and subprime mortgages as well as the elevated level of energy prices and rising interest rates," said Doug Duncan, the association's chief economist.

Rising interest rates can raise monthly payments for people on adjustable-rate mortgages. People who stretched financially to buy a home and have an ARM are more likely to feel the strain on their budgets from rising rates. Meanwhile, "subprime" borrowers — people with weaker credit records who are considered higher risks — also can face problems when rates rise and energy costs stay high.

If the impact of the hurricanes is removed from the mortgage survey, the fourth-quarter delinquency rate decreases to 4.55 percent, the association said.

The association's survey also showed that the percentage of mortgages that started the foreclosure process in the fourth quarter of last year edged up to 0.42 percent, from 0.41 percent in the third quarter. Even with the slight increase, the foreclosure figure is still considered low.

Duncan also said that one in eight U.S. mortgage borrowers "will get tested" by upcoming jumps in their monthly house payments.

About 25 percent of outstanding home mortgages carry adjustable interest rates due to adjust upward soon, he said.

"Half of those are seasoned," meaning the borrower is past the industry's three- to five-year danger peak for loan default and believed to have sufficient home equity or income to manage a higher mortgage payment, Duncan said.

But the other half of adjustable-rate mortgage customers "may have difficulty meeting their resets."

"As long as the economy continues to grow," Duncan said, "we expect the vast majority will be able to meet their higher payment."

He forecasts a 3.5 percent economic growth rate this year and at least 3 percent next year.

"But if the economy takes a nosedive, there will be job loss. Or if an economic shock led to a dramatic rise in interest rates, certainly that could change the trend," he said.

Duncan expects that most borrowers will avoid the worst-case scenario — foreclosure and loss of their house because of unpaid debt. That happened to just 1 percent of borrowers last year, his trade group's figures show.

"The last thing households will let go is the mortgage," he said. In most families, the mortgage bill is top priority, supplanted only in the depths of winter by the heating bill, he said.