Sales of new U.S. single-family homes unexpectedly fell in July to a nine-month low in a sign the housing market was cooling and could give less support to the overall economy.

The Commerce Department said on Thursday new home sales decreased 1.7 percent to a seasonally adjusted annual rate of 627,000 units last month, the lowest level since October 2017. June's sales pace was revised up to 638,000 units from the previously reported 631,000 units.

Economists polled by Reuters had forecast new home sales, which account for about 10 percent of housing market sales, rising to a pace of 645,000 units in July.

New home sales are drawn from permits and tend to be volatile on a month-to-month basis. They increased 12.8 percent from a year ago. Housing market data has weakened in recent months, with home resales declining in July for a fourth straight month.