U.S. homebuilding dropped more than expected in September as construction activity in the South fell by the most in nearly three years, likely held down by Hurricane Florence.

Housing starts fell 5.3 percent to a seasonally adjusted annual rate of 1.201 million units last month, the Commerce Department said on Wednesday. Data for August was revised down to show starts rising to a rate of 1.268 million units instead of the previously reported pace of 1.282 million units.

Starts in the South, which accounts for the bulk of homebuilding, tumbled 13.7 percent last month. That was the biggest decline since October 2015. Hurricane Florence slammed North and South Carolina in mid-September and flooding from the storm probably depressed homebuilding last month.

Building permits fell 0.6 percent to a rate of 1.241 million units in September. That was the second straight monthly decline in permits and suggested homebuilding is likely to remain tepid.

Economists polled by Reuters had forecast housing starts declining to a pace of 1.220 million units last month. Starts surged 29 percent in the Northeast and rose 6.6 percent in the West. They fell 14.0 percent in the Midwest.

The housing market has been a weak spot in a robust economy. Economists blame the sluggishness on rising mortgage rates, which have combined with higher house prices to make home purchasing unaffordable for some first-time buyers.

The 30-year fixed mortgage rate jumped 19 basis points to 4.90 percent last week, the highest level since mid-April 2011, according to data from mortgage finance agency Freddie Mac. The mortgage rate has risen about 91 basis points this year.

Single-family homebuilding, which accounts for the largest share of the housing market, decreased 0.9 percent to a rate of 871,000 units in September. Single-family homebuilding has lost momentum since hitting a pace of 948,000 units last November, which was the strongest in more than 10 years.

A survey on Tuesday showed confidence among single-family homebuilders rose in October, but builders said "housing affordability has become a challenge due to ongoing price and interest rate increases."

Permits to build single-family homes rose 2.9 percent in September to a pace of 851,00 units. They, however, remain below the level of single-family starts, suggesting limited scope for a strong rebound in homebuilding.

Starts for the volatile multi-family housing segment plunged 15.2 percent to a rate of 330,000 units in September. Permits for the construction of multi-family homes declined 7.6 percent to a pace of 390,000 units.