The number of buyers who agreed to purchase a home fell sharply in January, a sign that demand for housing is sinking this winter as stormy weather slammed Eastern states.

Record snowstorms in January and February had many Americans shoveling sidewalks and driveways instead of combing through listings for open houses. Partly as a result, an index that tracks sales agreements fell 7.6 percent from December to a seasonally adjusted January reading of 90.4, the National Association of Realtors said Thursday.

It was the lowest reading since last April and a disappointment to economists, who had expected it would rise to 97.6.