New York - A last-minute shopping surge helped holiday sales wrap up better than expected, according to one measure. But stores had to discount heavily to lure shoppers.

ShopperTrak, which tracks data at 40,000 stores in the U.S., said that sales for the November and December months combined rose 2.7 percent to $265.9 billion. That was better than the data service's 2.4 percent forecast for the season, but below the 3.0 percent gain in 2012.

The number of customers in stores dropped 14.6 percent from last year for November and December combined.

After a decent performance in November, sales at stores had been weak for most of December as shoppers held back for the best deals in a still challenging economy. Stores also were challenged by a season that was six days shorter than a year ago.

That put more pressure on stores for the last few days before Christmas. Merchants had been aggressive with discounting as early as late October but many stepped up price-cutting more than planned in the final days before Christmas.

"It was a lackluster season, but not devastating," Bill Martin, co-founder of ShopperTrak, said. "Stores had to go into deep discounting after the softness they saw."

In fact, the week ended Dec. 28 accounted for 15.5 percent of sales and 16 percent of all traffic for the holiday season. That compares with 10.9 percent of last year's holiday season sales and 11.5 percent of last year's traffic.

The numbers do not include online sales, which have been a bright spot for merchants but also faced some challenges.

Holiday shopping online rose 10 percent to $46.5 billion in November and December, the research firm comScore announced Monday. That was lower than the 14 percent growth expected as shoppers showed reluctance to spend freely and faced a shorter holiday season this year.

The results include sales from desktops and laptops but not mobile devices.

Online shopping has been a bright spot for retail sales, growing at a faster clip than overall spending. But the results were hurt primarily because of the six fewer shopper days, according to comScore Chairman Gian Fulgoni.

"Consumers did not have the same opportunity to buy that they would have in a more typical holiday season," Fulgoni said. "They made up for it to some extent by spending significantly more online on the weekends, but so many fewer workdays provided a headwind for the season that ultimately proved very challenging to overcome."

The National Retail Federation, the nation's largest retail trade group, is expected to release final holiday sales figures Tuesday. The group expects a 3.9 percent sales gain to $602.1 billion for November and December. That would be higher than the 3.5 percent increase seen in 2012. The figures include online sales.