WASHINGTON (Reuters) - Sales of new U.S. single-family homes rebounded in February as warmer weather and a decline in mortgage rates pulled buyers from the sidelines, but growing uncertainty over the economy's outlook could curb further gains.

New home sales increased 1.8% to a seasonally adjusted annual rate of 676,000 units last month, the Commerce Department's Census Bureau said on Tuesday. The sales pace for January was revised up to a rate of 664,000 units from the previously reported 657,000 units. 

Economists polled by Reuters had forecast new home sales, which make up about 15% of U.S. home sales, would rise to a rate of 679,000 units. New home sales are counted at the signing of a contract. They rose 5.1% on a year-on-year basis in February.

The median new house price fell 1.5% to $414,500 in February from a year earlier.