Holiday spending rose 4 percent in November and December compared with a year earlier, according to research firm ShopperTrak, despite a blizzard that slowed sales on the East Coast the day after Christmas.

Retailers' revenue rose 5.8 percent in November and 2.6 percent in December for a 4 percent rise overall compared with the same periods a year earlier. Meanwhile, traffic rose 4.6 percent in November and fell 2.6 percent in December, hurt by bad weather.

Rising revenue coupled with flat traffic suggests shoppers made fewer shopping trips but spent more when they got to stores.

Revenue on Black Friday, the day after Thanksgiving, was nearly flat at $10.69 billion as shoppers held out for bargains. Still, it was the top day for spending during the holiday season for the seventh year in a row.

ShopperTrak, which measures customer traffic in more than 70,000 stores, had previously said that a blizzard that swept through the Northeast on Sunday and Monday after Christmas delayed $1 billion in retail spending.