NEW YORK -- Before Hurricane Katrina devastated the Gulf Coast, the outlook for the holiday shopping season was already uncertain as consumers tried to fit higher gasoline prices into their budgets. The worries only escalated this past week in the aftermath of the hurricane, which threatened to take a toll on the economy as a whole.

Retailers who reported solid August sales figures on Thursday now fear they won't be able to extend that healthy sales pace. They're wondering whether consumers will curtail trips to the mall and buy fewer non-essentials as they pay more than $3 for gas in many parts of the country.

And merchants are well aware that holiday shopping will coincide with colder weather -- and home heating bills are expected to be up at least 20 percent from last year.

But Katrina has other consequences for consumers and businesses.

Higher energy costs will make it more expensive for merchants to heat their stores and transport goods, hurting margins in the critical fourth quarter. Industry analysts believe retailers will have to absorb higher costs for now, but consumers could end up paying higher prices on items from clothing to toys next year.

Logjams on the Mississippi River and at Gulf Coast ports could make a wide variety of goods including coffee, grain and raw materials like rubber, more expensive. Higher prices are bound to ripple over to consumers.

"I think shopper spending could be a train wreck under the Christmas tree," said Burt Flickinger III, managing director for New York-based Strategic Resource Group. He estimated there will be $35 billion less for consumer spending purchases for the holiday season as shoppers pay more for fuel and consumer goods.

Michael P. Niemira, chief economist at the International Council of Shopping Centers, said stores face their biggest challenge in four years, since the Sept. 11, 2001, terror attacks depressed Christmas sales.

"If Katrina was simply a devastation of the area, we could have weathered it," said Niemira. "But because of these ripple effects, Katrina is having a nationwide impact. There were already red flags out there, but this just makes us feel more uncomfortable."

Amid such uncertainty, Wal-Mart Stores Inc., whose lower-income shoppers have pulled back in the past year amid higher gasoline prices, tempered its September sales forecast due to Katrina. Mid-tier retailers such as J.C. Penney Co. Inc. and Kohl's Corp., whose consumers have so far been resilient despite oil's upward trek, may well see their shoppers retrench.

Meanwhile, upscale stores like Nordstrom Inc. could also be affected if customers don't feel in the mood to splurge amid graphic media coverage of floating bodies and human suffering -- the reaction they had to the 9/11 attacks.

Wendy Liebmann, president of WSL Strategic Retail, a New York marketing and retail consulting firm, believes shoppers will cut back on a variety of discretionary items, particularly fashion and high-end electronic items like flat-screen TVs. She added consumers may be even rethinking their purchases of small luxuries like $3 cups of gourmet coffee.

"I think there will be a lot of trading off," she said.

Already, a growing number of shoppers are rethinking their holiday purchases, with some saying they'll shop more for bargains and spend less overall. Some said they would buy more online or limit shopping trips to conserve gasoline.

"Last year, I spent around $500 on gifts. But this year, if gas and home heating bills continue to rise, I probably won't spend over $250," Rochelle Harris, a teacher from Atlanta.

Phoenix resident Maria Green, a business manager, said that if gas prices go up to $3.50, she would plan her shopping trips carefully, visiting stores that are clustered together.

"I would definitely consider mileage more heavily," she said.

Mike Shannon, of Rochester, N.Y., said he will be doing more Internet shopping. "It saves money on gas and it saves time so that you don't have to go walking through the malls," he said.

Over the past year, consumers felt more inclined to shop because they were more secure in their jobs and had more available cash due to mortgage refinancings. But interest rates are climbing, making it less attractive to refinance, and there are more concerns about jobs in Katrina's wake.

Beth Saunders, a personal assistant and masseuse in Phoenix, is already worried that her income will fall. "If people don't have money for gas, they're not going to have money for a massage," she said.

Concerns about consumer spending were exacerbated this past week when a government report showed the country's personal savings rate at the lowest level on record in July as people dipped into savings to finance their spending.

At least one economist is already muting his holiday forecasts in Katrina's aftermath.

Carl Steidtmann, chief economist at Deloitte Research, believes total sales in general merchandise will be up 4.0 percent to 4.5 percent for the combined November and December period, instead of his original forecast of 5 percent to 5.5 percent.

With only a few weeks until holiday merchandise reaches store shelves, merchants don't have much room to maneuver, although they could try to cancel some orders from suppliers if consumer spending decelerates as it did post-9/11. That will only cause further pain to manufacturers.

And while several major stores declined to comment about whether they will alter their strategies, the 2005 holiday season may bring bigger bargains than in past seasons as stores try to lure shoppers. That's good news for consumers.

This holiday season "will be highly competitive and highly promotional," said Liebmann. "There will be some pretty good deals out there."