The same region was hard hit by Hurricane Laura in August, leaving more than 6,000 people still living temporarily in hotel rooms and others with damaged homes. "We will get through this".
Tropical Storm Delta continued to weaken as it tracked farther inland over Louisiana on Saturday morning.
The biggest oil refinery in America had several key production units knocked out as Delta raged, according to people familiar with operations who asked not to be identified.
The hurricane has been downgraded to a tropical depression over western MS, the NHC said in a briefing note at around 10am local time (15:00 GMT), with winds of 55 kilometres per hour (35 miles per hour).
Arthur Durham, 56, was finishing covering windows at his home with plywood as protection against flying debris.
Delta, the latest in a recent flurry of rapidly intensifying Atlantic hurricanes that scientists largely blame on global warming, appeared destined to set records at landfall.
With the water knee-deep along Legion Street in Lake Charles, resident Patrick King had to wade through the water Saturday to get to his home after he returned from spending the night in Beaumont, Texas.
Lake Charles Mayor Nic Hunter said tarps flew off homes across the city, and in the building where he rode out the storm, a tarp flapping sounded "like someone pounding with a sledgehammer".
Delta, the 25th named storm of an unprecedented Atlantic hurricane season, is the first Greek-alphabet-named hurricane to hit the continental USA, and the 10th named storm to hit the mainland US this year, breaking a record set in 1916, said Colorado State University researcher Phil Klotzbach.
The storm triggered hurricane warnings stretching from High Island, Texas, to Morgan City, Louisiana.
Extreme Weather: Hurricane Delta Slams Louisiana Coast, Strong Winds Spread Inland
This week marked the sixth time of the current season that Louisiana has been threatened by tropical storms or hurricanes. It then moved over Lake Charles , a city where Hurricane Laura damaged almost every home and building in late August.
Delta, the 25th named storm of an unprecedented Atlantic hurricane season, made the record books when it struck the Gulf Coast.
As the tropical storm has moved further inland, Texas and MS residents also reported power outage.
"Damaging winds and a life-threatening storm surge continue over portions of southern Louisiana", the Miami-based centre said, adding that one monitoring site was reporting a storm surge of 2.4 metres above ground.
People in this battered coastal region were taking Delta seriously.
"You can always get another house, another vehicle, but not another life", said Hilton Stroder as he and his wife, Terry, boarded up their Abbeville home Thursday night with plans to head to their son's house further east.
By 7am (local time), Delta was centered near the Louisiana-Mississippi state line and barely a tropical storm.
Louisiana Governor John Bel Edwards had issued a State of Emergency on October 7 in anticipation of landfall. We could see the chance for localized flooding in some spots, along with a chance of flash flooding on roadways.
New Orleans, well east of the projected landfall area, was expected to escape Delta's worst impacts.
"Rapid weakening is expected overnight and Saturday", the NHC said. The depression was expected to bring heavy rain to eastern Arkansas and northern MS, generally totaling 2 to 4 inches, but with isolated storms bringing up to 10 inches and causing flash flooding.