Shoppers spent heavily last week both before and after Christmas, after a snow storm the last weekend of the holiday shopping season led to pent up demand.

Retail sales rose 8.8 percent during the week ending Dec. 26, according to research firm ShopperTrak. Meanwhile, traffic edged down 1 percent compared with a year ago.

On the day after Christmas, consumers spent $7.9 billion, up from $7.8 billion on the same day last year. That was the second biggest sales day of the season after "Black Friday," or the Friday after Thanksgiving, when shoppers spent $10.66 billion.

ShopperTrak continues to predict sales will rise 1.6 percent during the holiday season.

The firm, based in Chicago, tracks total retail sales at more than 50,000 outlets.