U.S. retail sales fell unexpectedly in January, as cold weather across much of the country contributed to a decline in spending on autos and other items, the government reported Thursday. The Commerce Department said retail sales fell 0.4 percent last month, marking the second consecutive decline after a 0.1 percent drop in December. Economists expected flat retail sales in January. Excluding autos, gasoline, building supplies, and food services, so-called core retail sales fell 0.3 percent in January after rising by 0.3 percent the previous month. Core sales correspond most closely with the consumer spending component of gross domestic product (GDP). Consumer spending accounts for 70 percent of U.S. economic activity. The weaker retail sales suggest that the momentum from consumer spending at the end of 2013 has halted this winter. Unusually heavy winter storms across the country reduced store traffic and limited post-holiday sales. Sales could continue to fall in February as winter storms continue.