Scenes From a Harsh Winter Sweeping the U.S.

Plunging temperatures have put much of the country in a deep freeze this holiday weekend, combining with snow, freezing rain, ice or gusty winds in some places to endanger nearly 100 million people from Northern California to coastal Maine.

Forecasters said hundreds of records gauging the cold could be broken this week, as frigid air gripped a huge swath of the nation, including southern cities like Dallas, Memphis and Little Rock, Ark. Other places braced for sleet or snow, with Buffalo, N.Y., expecting up to two feet of snow.

While some people hunkered down indoors, stocking up on food and firewood, others braved the cold to attend events for the Iowa caucuses, cheer on their favorite teams at the Chiefs-Dolphins N.F.L. playoff game or go skiing, among other activities.

Here’s a look at how Americans have faced the severe conditions.

A United Airlines jet was sprayed with de-icer at Kansas City International Airport in Kansas City, Mo., on Friday.

Attendees trekked through snow to get to a rally for Donald Trump in Indianola, Iowa, on Sunday.

People watched waves crash over the sea wall in Revere, Mass., on Saturday.

Vicki Kramer, director of the Nebraska Department of Transportation, motioned to a map of the state’s roads and current closures as she spoke during a news conference on Saturday in Lincoln, Neb.

Subzero temperatures in Chicago caused steam to rise from Lake Michigan on Sunday morning.

Floodwaters from the overflowing of the Schuylkill submerged Kelly Drive in Philadelphia on Wednesday.

Kelly Schoenfelt, center, her daughter Quinlynn, left, 6, and Parker Melowsky, 7, ran up Cricket Hill in the Uptown neighborhood of Chicago on Saturday.

Snow surrounded a tent on SE Grand Avenue in Portland, Ore., on Saturday.

Friendly House, a community center in Portland, Ore., opened as an emergency warming shelter on Saturday.

Workers removed snow from Highmark Stadium in Orchard Park, N.Y., on Sunday. A potentially dangerous snowstorm that hit the Buffalo region on Saturday led the N.F.L. to push back the Bills wild-card playoff game against the Pittsburgh Steelers to Monday from Sunday.

Tyson Ropp used an ax to break the ice covering a stock tank on Friday at the Double Cross Cattle Company ranch south of Roberts, Mont.

The Kansas City Chiefs on Saturday hosted a playoff game against the Miami Dolphins in subzero temperatures in Kansas City, Mo.

Gov. Greg Abbott of Texas spoke at a briefing on the state’s preparations ahead of the upcoming days of severe winter weather at the State Operations Center in Austin.

Katy Muelhaupt cross-country skied through downtown Des Moines on Friday.

Skiers took advantage of fresh snow at Mammoth Mountain Ski Area in Mammoth Lakes, Calif.

Isil Mico took a photo of her sister-in-law, Oznur Mico, in front of Snowzilla, a snowman measuring more than 20 feet tall, in Anchorage.