Although experts say the economy is booming, Harvard Square and Cambridge-area retailers are expressing cautious optimism as they head into this year's critical holiday shopping season.

For Cardullo's on Brattle Street, increased sales during the holidays can provide up to a quarter of the store's annual sales, according to Bz C. Ellis, the store manager.

"A little change in the weather in the second week of December can severely affect our sales figures," Ellis said.

"I think people feel like they have more money and are spending it. We have had more foot traffic and our average daily sales are far higher than last year," he said. Ellis attributed part of the success to the increased popularity of gourmet foods.

Cardullo's is not the only store whose prospects seem bright this holiday season.

Jerry A. Miller, the general manager at Cambridgeside Galleria, said, "We're expecting a good Christmas, up four to seven percent over last year."

Miller forecasted that the stores expecting the greatest sales gains are toy and electronics retailers.

Less robust, he predicted, would be he fashion and shoe segments, which Miller said would see only slight sales increases.