WASHINGTON—U.S. homebuilding dropped to a six-month low in February as severe cold gripped many parts of the country, in a setback for a housing market that remains supported by extremely lean inventories amid strong demand for larger homes. Housing starts fell 10.3 percent to a seasonally adjusted annual rate of 1.421 million units last month, the lowest level since last August, the Commerce Department said on Wednesday. Economists polled by Reuters had forecast starts would decrease to a rate of 1.560 million units in February. The deep freeze, which was most severe in Texas and other parts of the densely populated South region in the second half of February, dented retail sales and output at factories. Housing starts fell in the Northeast, Midwest, and South, but increased in the West. Permits for future home construction tumbled 10.8 percent to a rate of 1.682 million units last month. The year-long COVID-19 …