Officials have confirmed four deaths in Louisiana, two in Georgia, one in North Carolina and one in Houston.
More than 540 flights had been canceled by late Thursday afternoon, most to and from airports in Atlanta and North Carolina, according to the tracking site FlightAware.
Thousands of customers across Georgia and North Carolina had lost electricity, utility providers said, while several Louisiana parishes were under boil water advisories owing to busted pipes. Officials in Louisiana opted Thursday morning to keep portions of at least four interstate highways closed because of ice, they said, and state offices in parts of Georgia and Louisiana were due to remain closed for a second day.
Snow and icy conditions made roads in parts of the South and along the East Coast treacherous after a winter storm dumped snow Wednesday from the Florida Panhandle to Maine.
A swath of central North Carolina picked up more than 6 inches of snow, with some areas between Raleigh and Greensboro getting 10 inches. Some parts of New England got 6 inches.
'Do not drive'
One person was reported killed in North Carolina after a car ran off the road and fell into a canal in Washington County, Gov. Roy Cooper's office said in a news release.
Cooper said at a news conference earlier in the day that two people had died in that incident -- a driver and a passenger. But officials have since determined there was no passenger in the vehicle, according to the news release.
Since Tuesday evening, North Carolina troopers had responded to 3,500 calls, including 2,000 collisions, he said.
"The snow is beautiful," Cooper said, "but the roads are treacherous. Do not drive unless you absolutely have to."
Cooper pointed to a warning from retired stock car racer Dale Earnhardt Jr., who tweeted that North Carolinians should stay home, along with a photo of a stuck car attached to a line and winch on his vehicle.
"5 minutes after helping these folks I center punched a pine tree. All good. Probably just needs a new alignment," the winner of 26 races in NASCAR's top division said. Earnhardt tweeted again to clarify he was not in the crash but scratched the winch when he was driving too fast and "being a bit of a fool."
Two men died Wednesday in a traffic incident in Bibb County, Georgia, according to the local coroner. Both were traveling in a Honda Civic when the driver got out of the vehicle for an unknown reason, the county coroner, Leon Jones, told CNN. The driver of another vehicle lost control, striking the driver and the Civic, and killing both the driver and his passenger.
In West Feliciana Parish, Louisiana, a fire official was fatally injured Wednesday when a pickup truck pulling a trailer lost control on an icy road and hit the chief, who was investigating a previous crash, Louisiana State Police said.
Louisiana's governor's office confirmed three more fatalities in the state, Shauna Sanford, a spokeswoman for Gov. John Bel Edwards, told CNN. New Orleans Mayor Mitch Landrieu earlier had confirmed a death in his city in a weather-related accident.
In Houston, a homeless person died showing signs of hypothermia, the mayor and fire chief said.
Water pipes burst in cold
In Louisiana, frigid temperatures caused problems for municipal water systems with pipes that aren't well insulated because they aren't often exposed to extreme cold.
New Orleans officials expanded a precautionary boil water advisory to include the entire east bank of the Mississippi River, home to the French Quarter and the bulk of the city's population and tourism infrastructure.
The advisory was issued Wednesday after a drop in water pressure that was believed to have been caused by breaks in frozen pipes, according to a news release. Landrieu asked residents to limit water use to activities that were "absolutely necessary."
"Everybody can now clearly see that this prolonged freezing is stressing our critical water and power utilities in New Orleans and all surrounding parishes," Landrieu said.
St. John the Baptist and Lafourche parishes and the east bank of Jefferson Parish, just west of New Orleans, also implemented boil water advisories, Landrieu said. Jefferson Parish President Mike Yenni said it's the jurisdiction's first such advisory since Hurricane Katrina.
In Tennessee, which had the coldest pockets in the South, wind chills made the air feel as cold as 10 below zero.
Freeze warnings extended along much of the Gulf Coast into Florida.
Forecasters said chilly air would hang around from the South to the Northeast, leaving icy roads and hazardous conditions through Thursday, when temperatures began climbing.
"This morning the freezing temperatures stretched all the way down toward Orlando," said CNN meteorologist Judson Jones. "However, they're going to rebound really quickly today."
Orlando notched a 27-degree reading, the first time below freezing since January 2014.
By Thursday afternoon, temperatures throughout the South were above freezing. Most areas will see near "normal" weather temperatures through this weekend, Jones said.