Dangerously cold temperatures affected much of the Rockies, Great Plains and Midwest on Tuesday, with wind chills below minus 30 degrees in many parts of the central U.S.

Tens of thousands of U.S. homes and businesses were without power early Tuesday, according to PowerOutage.us, the bulk of them in Oregon after widespread outages that started Saturday. Portland General Electric warned that the threat of freezing rain Tuesday could delay restoration efforts. Transportation officials urged residents to avoid travel as roads were expected to be hazardously slick with ice that could weigh down trees and power lines, causing them to fall.

ERCOT, which manages the Texas power grid, appealed to customers for the second morning in a row to conserve electricity.

CBS Houston affiliate KHOU-TV says it took one commuter six-and-a-half hours to make the drive home from work Monday that usually takes a little more than a half-hour.

Classes were canceled Tuesday for students in Portland and other major cities including Chicago - home to the nation's fourth-largest public school district - Denver, Dallas, and Fort Worth, Texas.

Storms and frigid temperatures affected everything from air travel to NFL playoff games to Iowa's presidential caucuses, and caused of several deaths around the country.

At least four people in the Portland area died, including two from suspected hypothermia. Another man was killed when a tree fell on his house and a woman died in a fire that spread from an open-flame stove after a tree fell onto an RV.

In Wisconsin, the deaths of three homeless people in the Milwaukee area were under investigation, with hypothermia the likely cause, officials said.

The National Weather Service Chicago office said on X, the former Twitter that there was no relief in sight Tuesday:

Freezing rain and sleet were expected continue across portions of the Southeast Tuesday morning. Winter storm warnings were in effect for Lawrence, Limestone and Madison counties in Alabama and in Franklin County in Tennessee, southeast Arkansas, northeast Louisiana and much of northern, central and southwestern Mississippi.

Weather and Sports Updates

On Monday night, Olive Branch, Mississippi, and Jackson, Tennessee experienced a significant drop in temperatures, reaching as low as 10 degrees.

Despite frigid temperatures in the Northeast, fans braved the weather to support the Buffalo Bills at a snow-covered Highmark Stadium in Orchard Park, New York. The Bills emerged victorious in an AFC wild-card playoff game against the Pittsburgh Steelers. The game was delayed for 27-1/2 hours due to a storm that dumped over 2 feet of snow in the area. The Bills even sought assistance from the public to shovel the stadium.

In the coldest first-in-the-nation Iowa caucuses on record, voters awarded former President Donald Trump a victory on Monday night. Des Moines experienced temperatures as low as minus 3 degrees, with the wind chill making it feel even colder.

Although temperatures are expected to moderate midweek, a new surge of colder air is anticipated to move southward over the Northern Plains and Midwest. By the end of the week, it is predicted to reach the Deep South.