The National Weather Service warned of “life-threatening cold” into Tuesday, with temperatures in northeastern Montana predicted to dip as low as 45 degrees below zero (-42.7 degrees Celsius) with wind chills down to 60 below (-51 degrees Celsius).

Meteorologists said several states would experience the 10th and coldest polar vortex event this season. Weather forces in the Arctic are combining to push the chilly air that usually stays near the North Pole into the U.S. and Europe.

In Kentucky, Gov. Andy Beshear said Sunday that the death toll rose to nine.

“I am sad to share some more tough news tonight, Kentucky. We just confirmed another weather-related death out of Pike County, bringing our total loss to 9 people.”

Beshear had said earlier Sunday that at least 1,000 people stranded by floods had to be rescued. President Donald Trump approved Kentucky’s request for a disaster declaration, authorizing the Federal Emergency Management Agency to coordinate relief efforts throughout the state.

Beshear said most of the deaths, including a mother and 7-year-old child, were caused by cars getting stuck in high water.

“So folks, stay off the roads right now and stay alive,” he said.

Parts of Kentucky and Tennessee received up to 6 inches (15 centimeters) of rain, said Bob Oravec, a senior forecaster with the National Weather Service.

“The effects will continue for awhile, a lot of swollen streams and a lot of flooding going on,” Oravec said Sunday.

In Alabama, the weather service in Birmingham said it had confirmed an EF-1 tornado touched down in Hale County. Storms there and elsewhere in the state destroyed or damaged a handful of mobile homes, downed trees and toppled power lines, but no injuries were immediately reported.

A state of emergency was declared for parts of Obion County, Tennessee, after a levee failed on Saturday, flooding the small community of Rives, home to around 300 people in the western part of the state. “There will be mandatory evacuations in effect for the residents in Rives due to the rising water, no electricity, and freezing temperatures creating a life-threatening situation,” Mayor Steve Carr said in a statement Sunday.

In Atlanta, a person was killed when a large tree fell on a home early Sunday, according to Atlanta Fire Rescue Capt. Scott Powell.

Dangerously cold wind chill temperatures as low as 50 degrees below zero (minus 45.6) were expected in most of North Dakota, which remained under an “extreme cold warning” along with large swaths of South Dakota and Minnesota, according to the weather service.

Severe flooding

Water submerged cars and buildings in Kentucky and mudslides blocked roads in Virginia over the weekend. Flood warnings extended throughout Tennessee and Arkansas.

The mother and child were swept away Saturday night in Kentucky’s Bonnieville community, Hart County Coroner Tony Roberts said. In southeastern Kentucky, a 73-year-old man was found dead in floodwaters in Clay County, county Emergency Management Deputy Director Revelle Berry said. There were a total of four deaths in Hart County, Beshear said.

The Kentucky River Medical Center in the city of Jackson said it had closed its emergency department and transferred all patients to two other hospitals in the region due to a nearby river flooding.

High winds brought down trees and power poles across Albermarle County, Virginia. The Charlottesville Police Department said Sunday on social media that officers’ response times could be delayed due to “an overwhelming number of weather-related calls for service.” Police urged residents to stay off the roads.

Power outages were reported along much of the eastern seaboard, from New York south to Georgia.

In West Virginia, 13 southern counties were under a state of emergency for flooding and some areas were cut off to vehicle traffic Sunday. Several volunteer fire departments dealt with flooding in their own buildings while answering rescue and evacuation calls.

Rockies, Midwest, Northeast hit with snow storms, Polar Vortex on the way

Ice and snow made road travel treacherous in large swaths of Michigan, which remained under a winter weather advisory until Monday afternoon. Michigan State Police reported 114 crashes Sunday around the Detroit area since snow started falling Saturday.

“Fortunately, most were one-car spin outs and there were no serious injuries,” Michigan State Police said on X.

Authorities in Colorado reported eight people were killed in fatal vehicle crashes since Valentine’s Day and warned drivers to be cautious as the weather made driving more difficult. The causes of the fatal crashes weren’t immediately known.

Also in Colorado, three state patrol cruisers that had pulled over along roadsides were struck by other vehicles, including one on Sunday where a trooper had stopped as officials prepared to close a road because of ice. In each case the troopers were out of their cruisers at the time and were uninjured.

Avalanche warnings were issued for numerous areas of the Rocky Mountains stretching from Colorado to Washington state, with the danger rated highest in Utah.