Gulf Coast Braces for Rare Winter Storm as Brutal Cold Settles Across U.S.

Officials across a wide swath of the southern United States were closing schools, roads and even airports and urging residents to stay home on Monday as a significant winter storm was expected to bring heavy snow and frigid temperatures to areas unaccustomed to such weather, from Texas and Louisiana all the way to Florida.

The storm comes during an intense blast of arctic air across the country this week, with dangerous wind chill and icy conditions expected.

Up to 10 inches of snow are possible in some places where far smaller accumulations can snarl everyday life. The Houston metropolitan area was preparing for what could be “a historic snowfall in terms of modern history,” said Bradley Brokamp, a meteorologist with the National Weather Service there. The area could see between 4 and 6 inches of wet snow starting Monday night into Tuesday afternoon, he said.

The last time Houston recorded six inches of snow was in 1886. More recently, Houston recorded 2.5 inches of snow in 1973, he said.

Mr. Brokamp said the early morning commute on Tuesday could be “extremely dangerous” and that the National Weather Service was advising drivers to stay off the roads “at all costs,” he said.

More than 40 million people were under some form of severe winter weather advisory. The cold and snow shuttered school campuses across the South for Tuesday, and in some cases, through Wednesday as well, from Austin and Houston to Baton Rouge and New Orleans, to Tallahassee, Fla. There were delays announced in South Carolina and Georgia.

Elsewhere in the country, temperatures in the northern Plains and Upper Midwest were expected to hit the negative teens or single digits, and the Rockies, central Plains and Midwest were likely to see highs in the single digits or teens. With wind chills as severe as 20 to 30 degrees below zero expected along with snow, school closures were announced in parts of Iowa, Ohio and Minnesota.

The southern storm system is forecast to sweep across Texas, Louisiana, Mississippi, Alabama, North Florida, Georgia and the Carolinas, said Marc Chenard, a meteorologist at the Weather Service. Heavy snow is expected along and near the Interstate 10 corridor, while sleet and freezing rain are forecast for parts of southern Texas, southeast Georgia and northern Florida.

Numerous freeze warnings were in place in the Gulf Coast and northern Florida, as subfreezing morning temperatures could threaten sensitive plants and exposed plumbing. These frigid conditions are expected to persist for the next few days over eastern and southern parts of the country.

Department of Transportation workers in Texas and Louisiana were treating major highways with salt and brine ahead of the storm on Monday afternoon. The Texas transportation department said it had treated 3,000 lane miles of roads on Sunday.

Major travel disruptions, with flight delays and cancellations, are also anticipated, given these areas are not equipped to handle winter weather, Mr. Chenard added. The Houston Airport System, which includes George Bush Intercontinental Airport, William P. Hobby Airport and Ellington Airport, said it would shutter all flight operations beginning midnight Tuesday.

Total snow accumulations over southeast Texas and southwest Louisiana are expected to be between two and six inches.

At a news conference on Monday, officials in Louisiana implored residents to take precautions and stay off the roads. Below-freezing temperatures are predicted to last through Thursday in some areas, with possible snowfall of 4 inches or more across large swaths of southern Louisiana.

“This creates a very dangerous situation, not only for travel, but for people, pipes, pets and plants,” said Gov. Jeff Landry. He urged people to check their heating systems and warned against using gas or electric stoves or ovens to heat homes. Residents were advised to expect power or water supply disruptions and road closures.

Jay Grymes, the state climatologist, said that Southern Louisiana hadn’t seen a storm of this magnitude since the 1960s.

“Most of us haven’t experienced this combination of bitter cold and significant snow ever in our lifetimes,” Mr. Grymes said. “Take those precautions, take this event seriously. Get ready this evening, because you won’t have another opportunity until Thursday.”

Bitter cold and winter storm impacts are expected to linger across the Southeast and eastern United States until at least midweek. Dangerous driving conditions and travel disruptions are likely to continue for a few days in the South after the storm clears, Mr. Chenard said: “Given the cold air still in place, it might take a little while for things to melt out.”

Frigid temperatures in many areas will feel even more severe because of dangerous wind chills, particularly in the Rockies, northern Plains and Upper Midwest. These areas are forecast to have wind chills as low as 30 to 55 degrees below zero through Tuesday morning, levels that pose a severe risk of frostbite and hypothermia to anyone with exposed skin, the Weather Service warned. Even areas as far south as the south-central Plains and the Ohio Valley will experience subzero wind chills by the middle of the week.

At a homeless shelter in Kansas City, Mo., about 30 men took refuge from the 15-degree weather on Monday, including two people with frostbite, according to Eric Burger, the director of Shelter KC.

Victor Butler was there and said he had a tinge of frostbite on his feet.

Mr. Butler said that wearing multiple warm layers was not enough. “I knew I had insufficient clothing to make it through this type of cold,” he said.

Alexandra E. Petri and Lauren Kanan contributed reporting from Kansas City.