NEW YORK (MarketWatch) — Snowstorms that hammered the Northeast and socked in much of the eastern seaboard cost retailers’ sales an estimated 10% on Sunday and Monday, likely keeping about $1 billion from drifting into stores’ cash registers, according to mall-traffic tracker ShopperTrak.

A front-end loader is used to remove snow Tuesday from New York's Times Square. AFP/Getty Images

The two days after Christmas accounted for about $10 billion in sales, ShopperTrak estimated. Echoing other analysts and trade groups, the mall-traffic tracker said it expects the lost sales merely to have been postponed and to be made up as shoppers return to stores this week and through the New Year’s weekend.