Street crews dug out snow-clogged roads across the U.S. northeast on Friday after a powerful blizzard, with temperatures set to plunge further during a brutal cold spell that has already killed at least 18 people.

Extreme cold will reach from New England to the Midwest and down to the Carolinas, forecasters warned. Temperatures were expected to be 10 to 15 C below average across the northeastern United States for the next several days.

From Baltimore to Caribou, Maine, workers battled to clear snow and ice as temperatures with the wind chill were forecast to fall as low as – 40 C in some areas after sundown, according to the National Weather Service.

In the latest fatality blamed on the frigid weather, a driver slid off an icy road, killing a pedestrian, early on Friday in North Charleston, S.C., city officials said. The 17-year-old driver was arrested on charges including going too fast for the conditions, they said.

"THE DANGERS ARE REAL," the officials warned in a Twitter message. "Huge patches of ice all over the city. Stay at home."

In much of New England on Friday, temperatures will reach only about –21 C, with intense wind chills, said Dan Pydynowski, a meteorologist with private forecasting service AccuWeather.

"It can be very dangerous," Pydynowski said. "Any kind of exposed skin can freeze in a couple of minutes." 

Wind chill describes the combined effect of wind and low temperatures on bare skin.

Eastern U.S. hit by massive winter storm2:06

The extreme cold also raised the risk that road salt would not work to melt ice, possibly leaving highway crews to shift over to sanding roads to improve traction, Massachusetts transportation officials said.

Utility companies across the East worked to repair downed power lines as about 31,000 customers remained without electricity early on Friday, down from almost 80,000 the day before. Most of the outages were in West Virginia, Virginia and North Carolina.

Multiple fatalities

The storm that swept in on Thursday with winds gusts of more than 113 km/h dumped 30 centimetres or more of snow throughout the region, including Boston and parts of New Jersey and Maine, before ending early on Friday.

The harsh conditions were powered by a rapid plunge in barometric pressure that some weather forecasters called a bombogenesis, or a "bomb cyclone."

The weather has been blamed for at least 18 deaths in the past few days, including four in North Carolina traffic accidents and three in Texas.

Cities from Houston to Boston have stepped up efforts to bring the homeless to shelters. Authorities said that three homeless people in Texas died from exposure to the cold.

Numbing temperatures have also had some unusual effects — cold-shocked iguanas fell out of trees in Florida and wildlife officials in the state said they had rescued more than 200 stunned sea turtles from freezing waters.

Commuter railways serving New York and Boston's suburbs reported extensive delays as they worked to repair frozen equipment and clear snow-covered tracks.

Thursday's storm caused a 0.9-metre tidal surge that flooded the area around Boston's historic Long Wharf with icy seawater. Firefighters used an inflatable raft to rescue one motorist from a car submerged up to its door handles, Boston Fire Commissioner Joseph Finn told reporters.

Winter Weather Boston

A car sits in floodwaters from Boston Harbour on Long Wharf in Boston on Thursday. (Michael Dwyer/Associated Press)

Communities outside Boston, including Scituate, also experienced extensive flooding.

New York's John F. Kennedy International and LaGuardia airports resumed flights on Friday after closing during whiteout conditions the day before. More than 1,200 U.S. flights had been cancelled by midday on Friday. Most cancellations were at the three major airports in the New York area and at Boston Logan International Airport.

Nearly 500 members of the National Guard were activated to assist with the emergency response along the East Coast, including 200 in New York state, authorities said.