Dead include mother and seven-year-old daughter swept away in rains in Kentucky.
At least nine people have died after harsh winter weather struck the United States, including eight people in Kentucky as a result of heavy rains.
The state’s governor, Andy Beshear, said on Sunday that hundreds of people stranded by flooding had to be rescued.
Beshear said many of the deaths, including those of a mother and a seven-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.
“This is the search-and-rescue phase, and I am very proud of all the Kentuckians that are out there responding, putting their lives on the line.”
Beshear said the storms have knocked out power to about 39,000 homes, but he warned that harsh winds in some areas could increase outages.
Elsewhere, the Northern Plains faced life-threatening cold, and tornado watches were issued for parts of Georgia and Florida.
In Kentucky, Hart County Coroner Tony Roberts said earlier that the mother and child were swept away on Saturday night in the Bonnieville community.
In southeastern Kentucky, a 73-year-old man was found dead in floodwaters in Clay County, County Emergency Management Deputy Director Revelle Berry said.
Parts of Kentucky and Tennessee received up to 6 inches (15 centimeters) of rain during the weekend storms, said Bob Oravec, a senior forecaster with the National Weather Service.
“The effects will continue for a while; a lot of swollen streams and a lot of flooding going on,” Oravec said on Sunday.
In Atlanta, Georgia, a person was killed when an “extremely large tree” fell on a home early Sunday, according to Atlanta Fire Rescue Captain Scott Powell.
Meanwhile, heavy snowfall was expected in parts of New England and northern New York.
Meteorologists said the US was about to get its 10th and coldest polar vortex stretching event this season, with the northern Rockies and northern Plains first in line.
Weather forces in the Arctic are combining to push the chilly air that usually stays near the North Pole into the US and Europe.
