Sales of existing U.S. homes plummeted in January to the worst pace in 18 months. Cold weather, limited supplies of homes on the market and higher buying costs held back purchases.

The National Association of Realtors said Friday that sales fell to a seasonally adjusted annual rate of 4.62 million units last month. That was down 5.1 percent from the December pace. The sales rate declined 5.1 percent over the previous 12 months.