Nate weakened to a tropical storm early Sunday as it moved farther inland over Mississippi and Alabama, the National Hurricane Center said.
The storm had maximum sustained winds of 70 mph and "rapid weakening is anticipated," the center said.
Nate made its second US landfall near Biloxi, Mississippi, shortly after midnight local time Sunday as a Category 1 hurricane.
It was the first hurricane to make landfall in Mississippi since Hurricane Katrina in 2005.
Just hours earlier, Nate had made its first US landfall near the mouth of the Mississippi River in southeast Louisiana, with winds of 85 mph the National Hurricane Center reported Saturday night.
The center said that Nate was about 80 miles (130 kilometers) northeast of Biloxi early Sunday and heading northeast at a speed of 23 mph (37 kilometers an hour).
A hurricane warning has been discontinued for coastal areas from the mouth of Pearl River on the Louisiana-Mississippi border eastward to the Alabama-Florida border.
Nate triggered hurricane, tropical storm and storm surge warnings through a swath of the Gulf states, as residents braced for the third hurricane to hit the US mainland in six weeks.
Officials warned coastal communities of the storm surge, which is the height of water above dry ground. In Mississippi, the storm surge could reach up to 8 feet, according to the hurricane center.
Winds as fast as 89 mph were reported east of Venice, Louisiana, and 70 mph at Keesler Airforce Base in Mississippi.
Power was out for 267,000 customers in Mississippi, more than 50,000 in Alabama and 3,600 in Florida's Panhandle region, according to companies.
Meanwhile, rain soaked coastal Alabama, Louisiana and Mississippi much of Saturday. Nate could drop 3 to 6 inches of rain, with 10 inches possible in some areas, from the central Gulf Coast north across the Deep South, the eastern Tennessee Valley and the southern Appalachians through Monday, the hurricane center said. Flash flooding is a danger.
"Nate's center will continue to move inland over Mississippi and across the Deep South, Tennessee Valley, and central Appalachian Mountains through Monday," according to the National Hurricane Center's early Sunday advisory.
As the storm moves inland, it could mean more power outages, debris and flight delays, Sater said.
Nate has already carved a path of devastation in Central America. At least 28 people were killed Thursday in Costa Rica, Nicaragua and Honduras. Hundreds were rescued from floodwaters and mudslides. Many lost power and running water.
Emergencies declared in Mississippi, Louisiana
President Donald Trump declared an emergency in Mississippi and Louisiana.
Mississippi Gov. Phil Bryant urged county residents to head north away from the Gulf, but there was no mandatory evacuation. He warned winds could reach 80 mph and storm surge could be as high as 7 to 10 feet.
In Biloxi, Mayor Andrew Gilich was especially concerned about storm surge the storm could bring.
"The storm surge is a big thing that really traps everyone," he told CNN.
A dozen casinos in Mississippi took the rare step of closing early as the storm moved in.
There have been no reports so far of Nate causing injuries or major damage to homes in the city, according to Biloxi's public affairs manager, Vincent Creel.
"We were well aware that this could've been a much more serious storm. There was talk of it being a category 2 with an 11 feet tidal surge when it came ashore. It did not -- happily -- it did not live up to that billing," he said.
Biloxi will now access the damage.
"We're starting to see the water recede and we still have some wind gusts on the back end of the storm and we're going to have a lot of clean-up to do on our front beach. ... It's to be seen how much damage was done to the sand beach here in Biloxi and Harrison County," he said. "It looks like the beach took a pounding from the surge."
Alabama and Florida
In Alabama, Dauphin Island had "significant salt water flooding," Mayor Jeff Collier told CNN early Sunday. He said homes and cars were flooded, the causeway leading to the island closed and the west of the island inaccessible due to water up to six feet deep. The water had started to recede, Collier said.
The Port of Mobile closed Saturday, meaning the Carnival Fantasy cruise ship would not be "making its scheduled call" there Sunday, the Mobile Alabama Cruise Terminal said.
The Bankhead Tunnel, a major downtown thoroughfare that passes under the Mobile River, was closed because of the hurricane, emergency officials tweeted.
Florida Gov. Rick Scott, who had declared a state of emergency in 29 counties, said Saturday that evacuation orders were in effect for Escambia and Santa Rosa counties, with shelters open for those seeking higher ground.
Louisiana official: 'I think we dodged a bullet'
Nate moved east of New Orleans, sparing the city from the worst of the storm.
New Orleans had spent most of Saturday under a hurricane warning that was lifted around 7 p.m. CT. It was downgraded to a tropical storm warning and New Orleans Mayor Mitch Landrieu lifted a citywide curfew.
"I think we dodged a bullet," Louisiana Lt. Gov. Billy Nungesser told CNN's Brooke Baldwin on Saturday night. "I think we got the dry side of the storm."
Nungesser said he had been at Plaquemines Parish, which is at the southeast tip of the state.
"We saw no flooding or levees overtopping," he said.