A last-minute shopping surge helped U.S. holiday sales wrap up better than expected, 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 per cent to $265.9 billion US. That was better than the data service's 2.4 per cent forecast for the season, but below the 3.0 per cent gain in 2012.

The number of customers in stores dropped 14.6 per cent 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 recovering economy. Stores were also challenged by a season that was six days shorter than a year ago.

Last minute price-cutting

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

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

Online shopping up 10%

Holiday shopping online rose 10 per cent to $46.5 billion in November and December, the research firm comScore announced Monday. That was lower than the 14 per cent 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, due to the late American Thanksgiving, 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," said Fulgoni.

"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 predicting a 3.9 per cent sales gain to $602.1 billion for November and December. That would be higher than the 3.5 per cent increase seen in 2012. The figures include online sales.