At least 10 people were killed, including a young boy and a teenager, as storms barreled across the country Wednesday.
Two dozen twisters uprooted trees, ripped off roofs and wrecked vehicles across Iowa, Tennessee and Mississippi, according to the National Weather Service.
In Mississippi, three people and a dog were killed. A seven-year-old boy died after a tornado picked up a car he was traveling in, an official told the Associated Press.
Dozens of homes in the state were destroyed and small planes were overturned at an airport in Clarksdale.
"I'm looking at some horrific damage right now," Clarksdale Mayor Bill Luckett said, the AP reported. "Sheet metal is wrapped around trees; there are overturned airplanes; a building is just destroyed."
In Arkansas, an 18-year-old woman, identified as Michaela Remus, was killed when an uprooted tree crashed into her home as she slept. Her one-year-old sister was left trapped inside, but was later pulled to safety.
Two people, a man and a woman, lost their lives in Perry County, Tennessee.
Tornadoes also touched down in Indiana, ripping roofs off buildings.
Tornado damage near Holly Springs, MS... photos from David Moore pic.twitter.com/OyBMr9sTBB— James Spann (@spann) December 24, 2015
Holly Springs Motorsports Park… photos from Jeff Reed pic.twitter.com/VD1O0tVCXc— James Spann (@spann) December 24, 2015
The Storm Prediction Center had warned of "particularly dangerous" storms - the first time the alert had been issued since June 2014.
But as some people across the country hid from storms, others were enjoying balmier-than-usual temperatures.
In New York, the warmest December on record was previously in 2001, where the temperature averaged 44 degrees, CBS New York reported. This month, it is over 50.
Temperatures have been so warm that ice cream sales are up 26 percent, one store owner told the channel.
"It's too warm for me. I don't like it," Daniel Flores, a concierge in New York, told the AP. "I prefer the cold in the winter, in December. Gives you more of that Christmas feel."
Only about half of the nation can expect the possibility of a white Christmas, while a flood watch has been posted for parts of Georgia. More than four inches of rain is expected through Friday, the National Weather Service said.