At least 42 deaths have been attributed to the storm nationwide, according to the Associated Press.

In Fannin County, Texas, north of Dallas, three brothers died after falling into an icy pond, officials said.

In Frisco, Texas, near Dallas, a 16-year-old girl died from a sledding accident, according to Frisco police. The victim and another girl were being pulled on a sled by a teenage boy driving a car when the sled struck a curb and then hit a tree, police said.

In the Austin area, a victim was found dead in the parking lot of an abandoned gas station from apparent hypothermia, officials said.

In Arkansas, a 17-year-old boy died after he was pulled by an ATV in the snow and struck a tree, according to the Saline County Sheriff’s Office.

In Lehigh County, Pennsylvania, three people died while removing snow, the county coroner said. The victims ranged in age from 60 to 84, the coroner said, adding, "I remind the public to use caution when shovel snow … especially individuals with a history of heart disease or other medical concerns."

Eight people died in New York City and a retired police officer died on Long Island while shoveling snow, according to New York ABC station WABC.

Another man was found dead with a shovel in his hand in Verona, New Jersey, according to local police.

In Massachusetts, a woman died after a snowplow backed into her in a parking lot, local officials said.

Deaths were also reported in Tennessee, Louisiana, Mississippi, Kansas, Ohio and South Carolina, according to officials.

In Nashville, Tennessee, the Monroe Carell Jr. Children's Hospital at Vanderbilt has treated 46 children for carbon monoxide exposure since Sunday, hospital officials said.

The cases come as many families try to heat their homes during power outages caused by downed powerlines and fallen trees.

Carbon monoxide is an odorless gas and carbon monoxide poisoning can be fatal. Symptoms of carbon monoxide poisoning include dizziness, headaches, nausea and confusion.

To avoid carbon monoxide poisoning, never use generators or grills near open windows or vents, and make sure your battery-powered carbon monoxide detectors are working.

-ABC News’ Jason Volack

American Airlines said this was the most disruptive storm in the airline's 100-year history. American has canceled more than 9,000 flights and expects impacts to be felt for two more days.

American said 25% of its Tuesday flights are canceled. Across the U.S., more than 2,000 flights are canceled on Tuesday, with Dallas, Boston and New York hit the hardest.

Over 11,000 flights were canceled on Sunday, marking the highest day for cancellations since the pandemic, according to Cirium data.

-ABC News’ Sam Sweeney

More than 500,000 customers are still without power, with the worst outages in Tennessee, Mississippi and Louisiana.

The storm begins Friday afternoon with snow and ice in New Mexico and the Texas panhandle. By the evening, Dallas will see a wintry mix and Oklahoma City will see some snow.

Saturday is the most significant day for dangerous icing and heavy snow for the South.

On Saturday morning, the snow and ice will be stretching from Texas to Arkansas to Tennessee.

By Saturday afternoon, snow will be falling from St. Louis, to Indianapolis, to Cincinnati, to Charleston, West Virginia.

By Saturday evening, the snow and ice will cover a massive part of the country, stretching from New Mexico to the Carolinas.

Further south, a wintry mix or freezing rain will be hitting Dallas, Shreveport, Louisiana, Memphis, Tennessee, and Raleigh, North Carolina.

The storm will move east early Sunday, bringing snow from Wichita, Kansas, to Cincinnati, to Washington, D.C., to Philadelphia.

Freezing rain will be likely by sunrise in Houston, Memphis, Atlanta and Raleigh.

By noon, the snow will reach New York City, while the snow in D.C. will warm to a wintry mix.

It’s not yet clear which parts of the Interstate 95 corridor will get a wintry mix and which will get all snow on Sunday afternoon. But most of New England and the interior Northeast will see all snow on Sunday and early Monday.

A wide swath of plowable snow -- 3 to 6 inches -- is forecast from New Mexico through the Ohio Valley and up to Maine.

The heaviest snow is expected to be from the Texas panhandle to southern Missouri, as well as from the Ohio Valley to the Appalachian Mountains and New England.

In the Northeast, a large swath of the region could see over 1 foot of snow, with 6 to 12 inches forecast closer to the coast, from Virginia to southern New England coast. New York City’s latest forecast shows 8 to 12 inches.

-ABC News' Kyle David and Dan Peck