Tens of thousands of homes and businesses remain without power on Saturday after being hit by a different icy storm last week.
About 240 million people were under cold weather advisories and winter storm warnings, a forecaster said.
The frigid cold was expected to plunge as far south as Florida. Some areas unaccustomed to snow were bracing for several centimetres to fall by Sunday.
The powerful winter storm system came after another blast of snow and ice last weekend snarled traffic, knocked down trees, and caused more than 100 deaths.
A low temperature of minus 33C was recorded Saturday morning in West Virginia, said Bob Oravec, lead meteorologist for the National Weather Service in College Park, Maryland.
Parts of the southern Appalachians, the Carolinas and Georgia could see 15-25cm of snow, he said.
The Carolinas could see blizzard conditions stemming from the bomb cyclone, a term Oravec used to described an intense, rapidly strengthening storm system off the southeast coast packing strong winds.
"Anytime you have cold weather advisories or extreme cold warnings, it is dangerous to be outside. Frostbite can occur," Oravec said.
"Especially in areas that have or are experiencing power issues still, prolonged exposure to cold weather is not good for yourself."
In Myrtle Beach, South Carolina 15cm of snow was expected. The city has no snow-removal equipment, and authorities planned to "use what we can find", Mayor Mark Kruea said.
Subfreezing weather was forecast into February, with heavy snow in the Carolinas, Virginia and northeast Georgia over the weekend, including up to 30cm in parts of North Carolina. Snow was also said to be possible from Maryland to Maine.
More than 197,000 homes and businesses were without electricity, mostly in Mississippi and Tennessee, according to the outage tracking website poweroutage.us. That included nearly 48,000 in Nashville as of Saturday morning.
Amanda Linton, a resident of Holly Springs, Mississippi, which sits near the border of Mississippi and Tennessee, said her family tried to keep busy and stay positive during the week-long outage.
The family of five have been stuck in the house for days with their dogs, chickens and ducks as the roads are covered with inches of compacted ice.
Linton said they managed to buy a generator in preparation ahead of the storms.
"Just lots of games and reading and really just trying to keep mine and my husband's spirits up so that we're staying positive for our kids," Linton said.
Tennessee Governor Bill Lee said he shared "strong concerns" with leadership of Nashville Electric Service. The utility has defended its response, saying the storm that struck last weekend was unprecedented.
Mississippi officials said the massive winter storm was its worst since 1994. About 80 warming centres were opened, and National Guard troops delivered supplies by truck and helicopter.
Experts warned of the growing risks of hypothermia. Frostbite was also a concern in the South, where some people may lack sufficiently warm clothing, said David Nestler, an emergency medicine specialist at the Mayo Clinic in Minnesota.
More than 100 people have died from Texas to New Jersey, roughly half of them in Tennessee, Mississippi and Louisiana. While some deaths have been attributed to hypothermia, others are suspected to be related to carbon monoxide exposure. Officials have not released specific details about some deaths.
In North Carolina, hundreds of National Guard soldiers readied to help and state workers worked to prepare roads.
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