Oklahoma City (AP) More than 10,000 flights across the US set to take off over the weekend were cancelled as a monster storm started to wreak havoc Saturday across much of the country and threatened to knock out power for days and snarl major roadways with dangerous ice.

Roughly 140 million people, or more than 40 per cent of the US population, were under a winter storm warning from New Mexico to New England. The National Weather Service forecast warns of widespread heavy snow and a band of catastrophic ice stretching from east Texas to North Carolina.

All Saturday flights were cancelled at Will Rogers International Airport in Oklahoma City, and all Sunday morning flights also were called off, as officials aimed to restart service Sunday afternoon at Oklahoma's biggest airport. The airport was nearly deserted Saturday morning, with only a few TSA agents and a couple of travellers remaining inside the departures side.

The Texas Department of Transportation on Saturday posted images of snow-covered highways in the suburbs north of Dallas. Ice and sleet that hit northern Texas overnight moved toward the central part of the state on Saturday.

“It's happening!” the transportation agency's post said.

By mid-morning Saturday, ice had formed on roads and bridges in a third of Mississippi's counties, according to Scott Simmons, a spokesman for the Mississippi Emergency Management Agency.

Little Rock, Arkansas, was covered with sleet and snow Saturday morning, giving Chris Plank doubts about whether he would be able to make a five-hour drive to Dallas for work on Sunday. While some snow was a yearly event, he could only recall three ice storms in the previous 20 years that he had lived in Little Rock, and that potential ice concerned him the most.

“All of the power lines are above ground, so it doesn't take very much to end up in the dark,” Plank said Saturday morning.

Forecasters say damage, especially in areas pounded by ice, could rival that of a hurricane.

“Dangerously cold temperatures and wind chills are spreading into the area and will remain in place into Monday,” the agency said on X. Low temperatures will be mostly in the single digits for the next few nights, with wind chills as low as minus 12 degrees Fahreinheit (minus 24 Celsius).

More than 95,000 power outages were reported across the country Saturday morning, about 36,000 of them in Texas and 10,000 more in Virginia. Snow and sleet continued to fall in Oklahoma.

Governors in more than a dozen states sounded the alarm about the turbulent weather ahead, declaring emergencies or urging people to stay home.

As of 10 am ET, more than 3,800 flights were cancelled Saturday, according to the flight tracking website FlightAware. Almost 7,000 flights were called off for Sunday.

Angela Exstrom was supposed to fly back to Omaha, Nebraska, from a trip in Mexico, but she learned her Saturday flight out of Houston had been cancelled. So instead, she is going back via Los Angeles.

“If you live in the Midwest and travel in the winter, stuff can happen,” she said.

After sweeping through the South, the storm was expected to move into the Northeast, dumping about a foot (30 centimetres) of snow from Washington through New York and Boston, the weather service predicted. Temperatures reached minus 29 F (minus 34 C) just before dawn in rural Lewis County and other parts of upstate New York after days of heavy snow.

Frigid temperatures and ice ------------------------------ Utility companies braced for power outages because ice-coated trees and power lines can keep falling long after a storm has passed.

The Midwest saw wind chills as low as minus 40 F (minus 40 C), meaning that frostbite could set in within 10 minutes. The minus 36 F (minus 38 C) reading in Rhinelander, Wisconsin, on Saturday morning was the coldest in almost 30 years.

In Bismarck, North Dakota, where the wind chill was minus 41 (minus 41 Celsius), Colin Cross was bundled up Friday in long johns, two long-sleeve shirts, a jacket, hat, hood, gloves and boots as he cleaned out an empty unit for the apartment complex where he works.

“I've been here awhile and my brain stopped working,” Cross said.

Workers from The Orange Tent Project, a Chicago nonprofit that provides cold weather tents and other supplies to unhoused individuals throughout the city, went out to check on those that did not or could not seek shelter.

“Seeing the forecasted weather, I knew we had to come out and do this today,” said CEO Morgan McLuckie.

Government prepares to respond ----------------------------------- The federal government put nearly 30 search and rescue teams on standby. Officials had more than 7 million meals, 600,000 blankets and 300 generators placed throughout the area the storm was expected to cross, according to the Federal Emergency Management Agency.

President Donald Trump said via social media on Friday that his administration was coordinating with state and local officials and “FEMA is fully prepared to respond.” Nine states have requested emergency declarations, according to a FEMA briefing document released Saturday. The declarations can unlock federal emergency resources. Trump on Friday approved emergency declarations for South Carolina and Virginia, and requests from Arkansas, Kentucky, Louisiana, Maryland, North Carolina, Tennessee and West Virginia were still pending as of Saturday morning.

After the storm passes, it will take a while to thaw out. Ice can add hundreds of pounds to power lines and branches and make them more susceptible to snapping, especially if it's windy.

Church, Mardi Gras and classes cancelled -------------------------------------------- Churches moved Sunday services online, and the Grand Ole Opry in Nashville, Tennessee, decided to hold its Saturday night radio performance without fans. Mardi Gras parades in Louisiana were canceled or rescheduled.

Schools superintendents in Philadelphia and Houston announced that schools would be closed Monday.

Some universities in the South cancelled classes for Monday, including the University of North Carolina at Chapel Hill and the University of Mississippi's main campus in Oxford. (AP) RD RD