After a freezing winter storm shut schools, cut power and canceled or delayed flights, the South was slowly thawing Sunday.

Crews worked furiously and by Sunday morning power had been restored to parts of North Carolina and South Carolina where tens of thousands of customers lost electricity over the last few days, according to Duke Energy.

Power was back for 97% of the retail customers served by Georgia Power — the state largest utility — which serves all but four of the state’s 159 counties, it said.

“Crews have not slowed down, in fact, we have brought in additional resources to help us get across the finish line,” a press release on The City of Atlanta Government’s Facebook page read.

Much of the winter weather has moved out of the area, said Dylan Lusk, a National Weather Service meteorologist in Peachtree, Georgia.

“For the most part, we are slowly warming up and finally thawing a little bit after snow fall and a coating of freezing rain,” Lusk said.

Warmer weather was expected but some areas were still dealing with ice. Authorities warned people to drive slowly and be careful with slick spots on roads — especially when temperatures drop again at night and melted snow and ice refreezes.

“Black ice will return as temperatures drop below freezing this evening through Monday morning,” the National Weather Service said.

Planes needed deicing and more than 100 flights to and from Hartsfield-Jackson Atlanta International Airport were delayed on Sunday — an improvement from Saturday, when 1,000 flights were cancelled or delayed, according to FlightAware.com. By mid-afternoon Sunday operations had returned to normal, airport officials said.

Earlier this week the storm brought heavy snow, as much as 7 inches in some spots, and made roads slick across much of Texas and Oklahoma before moving east.