After making landfall Friday evening near Creole, Louisiana, Hurricane Delta moved inland, dumping rain and whipping southwestern Louisiana.
The storm, which roared ashore as a Category 2, had been downgraded to a tropical storm by early Saturday with maximum sustained winds of 60 mph. Tropical storm conditions and heavy rain were still pounding much of the state, the National Hurricane Center said.
Delta's attack came only six weeks after Hurricane Laura battered nearly the same area. Delta is the 10th named Atlantic Basin-season storm to strike the United States mainland, a record number that some scientists are correlating to climate change.
Phil Klotzbach, atmospheric research scientist at Colorado State University, said on Twitter Friday Delta is the fourth named storm to strike Louisiana this season, a number that ties a record from 2002.
Storm surges remain a threat, with 4 to 6 feet possible for the coast from the Rockefeller Wildlife Refuge to Morgan City, with storm surges in the feet also possible for other parts of the Louisiana coast, forecasters said.
The center of the storm will move across northern Mississippi and into the Tennessee Valley on Saturday and Sunday, and it is expected to become a tropical depression later Saturday.
Powerful waves driven by the storm hit the shore southwest of Houston on Friday morning, as shown in a video of San Luis Pass uploaded by Twitter user @dynamogal.
"The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline," the National Hurricane Center said.
Six million people from Louisiana to Mississippi and western Tennessee were under flash flood watches Friday. It's the sixth time this season that people in Louisiana have braced for a hurricane.
About 440,000 power customers in Louisiana were without electricity Friday night.
Delta struck the shore about 39 miles from Lake Charles, a community devastated by Tropical Storm Laura in August.
Lake Charles is in the heart of the state's Cajun country, a historically French-influenced area.
Local residents told NBC News people there are weary of powerful hurricanes this season.
"Emotionally, I think everybody is just battered and worn down right now," one Louisiana resident told NBC News.
Hurricane Laura ripped roofs off homes and cut trailers in half. About 20 percent of homes in that area still have blue tarps as temporary roofs after that storm.