ANNAPOLIS, Md. — A huge swath of the U.S. was blasted with ice, snow and wind on Monday as the polar vortex that dipped south over the weekend kept much of the country east of the Rockies in its frigid grip, making many roads treacherous, forcing school closures, and causing widespread power outages and flight cancellations.

The immense storm system brought disruption to areas of the country that usually escape winter’s wrath, downing trees in some Southern states, threatening a freeze in Florida and causing people in Dallas to dip deep into their wardrobes for warm hats and gloves.

Washington, D.C., received heavy snow as President-elect Donald Trump’s victory was certified. Taking advantage of the rare snowstorm in the nation’s capital, revelers engaged in a snowball fight in front of the Washington Monument as flags flew at half-staff in memory of former President Jimmy Carter.

In Kentucky’s biggest city, Louisville, Hugh Ross used his shovel Monday to break sheets of ice that were covering his driveway. Frozen rain fell atop snow that arrived Sunday, which he said “couldn’t have been worse.”

“You’ve got to break it up first,” Ross explained. “If you don’t do that, you’re wasting your time. I did a couple of layers yesterday, so I had to make sure I wasn’t in too bad of shape today.”

Ice and snow blanketed major roads in Kansas, western Nebraska and parts of Indiana, where the National Guard was activated to help stranded motorists. The National Weather Service issued winter storm warnings for Kansas and Missouri, where blizzard conditions brought wind gusts of up to 45 mph. The warnings extended to New Jersey into early Tuesday.

At the storied Calumet Farm in central Kentucky, the thoroughbreds were led to their stalls Sunday afternoon before freezing rain turned their pastures into a slick glaze of snow and ice.

“The ice is the worst part,” Eddie Kane, the farm manager, said Monday. “I still haven’t turned them out because it’s still a little bit too dangerous. It’s like an ice-skating rink out there in the fields.”

In his central Missouri apartment complex’s parking lot, Gary Wright wore a parka as he and his husband chipped away at the ice coating his SUV. Wright, a 33-year-old North Carolina native, said he would work remotely on Monday but wanted to scrape off his vehicle as an excuse to spend time in the snow.

The polar vortex of ultra-cold air usually spins around the North Pole, but it sometimes plunges southward into the U.S., Europe and Asia. Studies show that a fast-warming Arctic is partly to blame for the increasing frequency of the polar vortex extending its grip.

Temperatures plunge

Starting Monday, the eastern two-thirds of the U.S. dealt with bone-chilling cold and wind chills, said forecasters, predicting that temperatures could range from 12 to 25 degrees below normal in many areas.

The Northeast, which has had a relatively mild start to winter, was expected to get several cold days, said Jon Palmer, a weather service meteorologist based in Gray, Maine.

The cold air was expected to grip the Eastern Seaboard as far south as Georgia, with temperatures dropping into the low single digits in some coastal areas, Palmer said.

Classes canceled

School closings were widespread, with districts in Indiana, Virginia, Kentucky, Missouri and Kansas canceling or delaying the start of classes Monday. Among them was Kentucky’s Jefferson County Public Schools, which canceled classes and other school activities for its nearly 100,000 students.

Classes were also canceled in Maryland, where Gov. Wes Moore declared a state of emergency Sunday and announced that state government offices would also be closed Monday.