Freezing rain fell across much of the Great Plains and Midwest on Saturday as a major ice storm already blamed for the death of a motorist in Missouri and dozens of cancelled flights threatened to wreak further havoc.

Ice, freezing rain and winter weather warnings and advisories were in effect for a vast swath of the country stretching from northern Texas east across parts of the Midwest and into the Washington, D.C. area, according to the National Weather Service.

"Ice continues to accumulate in the Central/Southern Plains states and will shift north into the Upper Mississippi Valley Sunday as a new weather system approaches from the West Coast," the Weather Service said on its website.

"This storm will change ice to snow from southeast Colorado to northeast Nebraska; and will bring a slight risk of severe thunderstorms and heavy rains to Texas on Sunday," the Weather Service said.

The Missouri State Highway Patrol urged motorists to avoid travel after 31-year-old Tiffany Jackson was killed while driving on any icy overpass in Crystal City.

Jackson's vehicle slid off the road and struck trees, according to the highway patrol. Forecasters said ice accumulation from the storm could be more a centimetre. 

Southern Plains-Ice Storm

A Missouri Department of Transportation salt truck spreads ice melt on Interstate 55 as coated tree branches sway overhead as seen from the Main Street bridge on Friday. (Robert Cohen/St. Louis Post-Dispatch/Associated Press)

States of emergency

Snow, sleet and heavy fog were also in the forecast in parts of region. Missouri and Oklahoma had declared states of emergency ahead of the storm as transportation officials in those states told motorists to avoid travel.

The Lambert-St. Louis International Airport told passengers to check with airlines as the weather "could potentially impact flights."

Will Rogers Airport in Oklahoma City warned of "multiple delays and cancellations."

Southern Plains Ice Storm

Icicles hang from a street sign as freezing rain falls in Enid, Okla., Friday. (Billy Hefton/The Enid News & Eagle via Associated Press)

Airline tracking website showed 435 flights had been canceled and nearly 5,000 delayed as of the afternoon.

Local news in Kansas City showed footage of shoppers rushing through stores to stock up on essentials.

"Getting stocked up for the upcoming ice storm and shelves are already empty," tweeted Valerie Mia Juarez, a journalist in Nebraska, with a photo showing one loaf of bread on a bare shelf at a local Walmart.

The National Football League postponed the start time of a divisional playoff game between the Kansas City Chiefs and the Pittsburgh Steelers in Kansas City from around noon local time on Sunday to 7:20 p.m.

As of Saturday morning, about 2,500 households and businesses were without power in Texas, Missouri and Oklahoma, utility companies reported.

The weather system may affect Canada by Tuesday, but it "won't be as bad for us as it will for them" as it turns into rain, said the Weather Network's Chris St. Clair.

"Only the Ottawa Valley and across Sudbury, North Bay and Sault Ste. Marie may get more than five hours of freezing rain," he said.

With files from CBC News