The National Weather Service said late Sunday night that a winter storm warning for most of North Texas had been replaced with a winter weather advisory through noon on Monday.

A mix of rain, light freezing rain and light sleet was expected, but meteorologist Steve Fano with the weather service's Dallas-Fort Worth office said the temperatures would not be as cold as initially forecast.

"They will still go below freezing in some places, just not as much below freezing as we initially thought," Fano said.

Meteorologists said they expected the Arctic mass to head south and east and threaten plans for Tuesday and Wednesday as people hit the roads and airports for some of the busiest travel days of the year in the United States.

More than 300 flights were canceled at Dallas-Fort Worth International Airport, representing about one-third of the scheduled departures, and a spokeswoman said de-icing equipment had been prepared as officials planned for the worst in a flurry of conference calls and meetings.

"It's certainly going to be a travel impact as we see the first few people making their way for Thanksgiving," weather service meteorologist Tom Bradshaw said.

With most of the precipitation expected to occur during the overnight hours on Sunday into Monday, Fano stressed the need for motorists to be cautious on the roads, especially as they head to work during the morning rush.

"If nothing else, roads are going to be wet and it's going to be cold, so caution definitely is advised in travelling," he said.

A mix of rain and sleet began falling north of Dallas on Interstate 35 by midday Sunday. Some elevated overpasses had icy surfaces.

Parts of Oklahoma have been under a winter storm warning, while other areas of the state have been under an advisory.

Some communities in southwestern Oklahoma woke up to snow Sunday, including Altus, where several inches fell. "It looks great. I love the snow," said Damaris Machabo, a receptionist at a Holiday Inn motel.

The snow and freezing temperatures made driving in the area treacherous, but Machabo said she had no problems getting to work early Sunday. Forecasts called for more snow in the area later in the day.

Portions of New Mexico — especially in some of the higher elevations — also had several inches of snow, and near white-out conditions were reported along stretches of Interstate 40 west of Albuquerque.

Then along the New Mexico-Texas border, into the El Paso area, a mix of snow, sleet and ice forced some road closures and created messy driving conditions.

Flagstaff in Arizona had 28cm of snow by early Sunday, and was expected to get another inch by the end of the day before the storm petered out. Metro Phoenix and other parts of central Arizona received between 3.8 to 6.35cm of rain over the course of the storm.

The storms caused cancellations of sporting events and parades and damaged the roofs of homes across Arizona.

In Tucson, firefighters on Friday recovered the body of a man who was swept away by high water in the Santa Cruz River.

Tucson police said Sunday an autopsy revealed signs of trauma, and they were investigating the death as a homicide. They did not say whether they had ruled out the storm as a cause of his death.

By early Sunday, the weather was blamed for at least eight deaths in several fatal traffic accidents. The storm also caused hundreds of rollover accidents, including one that injured three members of singer Willie Nelson's band when their bus hit a pillar on Interstate 30 near Sulphur Springs, about 120 kilometres northeast of Dallas.

Dallas prepared for the storm by declaring "Ice Force Level 1," which is code for sending 30 sanding trucks to troubleshoot hazardous road conditions.

At Dallas-Fort Worth International Airport, spokeswoman Cynthia Vega said most of the cancelled flights were in the afternoon and evening hours and were with American Airlines and American Eagle. The possibility of ice on the runways led to a series of conference calls and meetings early Sunday, she added, noting the airport had liquid and solid deicers ready for use.

The storm system, though, was particularly hard to predict because a couple of degrees here or there with the temperature will determine whether regions see rain, sleet or snow, Bradshaw said.

"It's very difficult to pin those down," he said. "It's slow moving and it's sort of bringing its energy out in pieces so it's kind of hard to time these as they come across with a great deal of accuracy."

AP