Freezing rain, snow and ice swirling in and around unseasonably warm patches created a bizarre patchwork of weather conditions over dozens of states Sunday, wreaking havoc for millions of holiday travelers.
The massive storm, covering at least 35 states, carried a little bit of everything:
Heavy snow from Oklahoma to Wisconsin — as much as 10 inches predicted through Sunday.
Flash flood watches across 11 states from Texas to New York.
Ice storm warnings in parts of northern New England.
Record highs in other parts of the Northeast.
Possible tornadoes, with the highest risk Monday from Texas to Tennessee.
"What really worries me tornado-wise about this situation is one, people don't usually expect tornadoes in December," said Greg Forbes of The Weather Channel. "Two, they are going to be in some cases farther north than people expect."
The Midwest, meanwhile, was digging out from another major snow dump. Parts of Iowa had recorded 6 inches by 5 p.m. ET Sunday, and dangerously cold air was moving in behind it to lock in ice hazards.
With wind chills expected as low as minus-25 in some counties overnight, Alex Mihalakis and his 6 year-old-son, Jace, were out helping clear off sidewalks, cars and driveways in Dubuque for people who weren't able to get out.
"We can't buy anybody anything, so we decided to help them out with this snowfall," Mihalakis told NBC station KWWL of Waterloo.
"We've had pretty poor weather conditions two weeks in a row leading up to Christmas," said Christopher Dolce, a meteorologist for The Weather Channel. "There's been a considerable amount of winter storm activity all the way back to the days before Thanksgiving and a lot of travel woes continuing into December."
About 665 flights had been canceled and 5,750 more had been delayed across the country at 9:30 p.m. ET Sunday, according to the aviation tracking website FlightAware.com.
Many were in or out of major hubs like Houston's Bush International, Dallas/Fort Worth, Denver International and Chicago's O'Hare Airport, where 136 flights had been canceled.
The weather was suspected in at least eight deaths, including that of a driver who was killed Saturday afternoon on an icy road near Kansas City, Mo., police said, and two people in Mississippi who were killed as a result of gusty winds.
Five people also drowned in Kentucky, NBC station WLWT of Cincinnati reported — three in one vehicle in Bardstown, which became submerged in the Rolling Fork River, and another man in Carroll County, whose vehicle tipped over on top of him after getting stuck in a creek. A fifth body was recovered from an abandoned vehicle in a flooded ditch in Ballard County.
The large storm system surged into the Midwest on Friday. On Saturday night, a line of thunderstorms stretched from southern Louisiana to Indiana, and at least two suspected tornadoes hit Arkansas, injuring at least five people.
A man in Rena Lara, Miss., was killed Saturday when wind flipped his mobile home.
And another person died Saturday when the car he was driving struck a fallen tree in the road in Jasper County, Miss. A woman in the car was critically injured and taken to the hospital.
Meanwhile, a major ice storm was barreling toward New York State and northern New England, knocking out power to thousands of customers. About 52,000 customers in upstate New York and 315,000 in Michigan were affected, utility officials said.
But balmy, warm weather was also moving ahead of the front, with other parts of the East Coast seeing highs in the 70s along with high humidity. New York City's Central Park hit a record 65 degrees Saturday.
The system created wildly swinging weather patterns almost county to county. In Bennington, Vt., the high reached 63 degrees Sunday, compared to 37 in Albany, N.Y. — only 40 miles west.