Some 60 million people, across more than a dozen states from Kansas to New Jersey, have been left under winter storm warnings, advisories or watches today.
The storm was moving toward the mid-Atlantic, where Washington DC was bracing for heavy snow and bitter cold, the same day the US Congress is set to meet and formally certify Republican Donald Trump's election as president.
Republican House Speaker Mike Johnson told Fox News yesterday the weather would not prevent lawmakers from carrying out their duties.
Kansas and parts of northwestern Missouri were enduring blizzard conditions into Sunday afternoon, the National Weather Service said. Roadways were blanketed in snow and ice, and officials urged residents to avoid travel.
Total snowfall of between 15cm and 30cm was expected from southern Ohio to Washington.
In northern Kentucky and southern West Virginia, freezing rain and sleet will produce "hazardous ice accumulations," the service said. The back end of the storm system, meanwhile, was producing severe thunderstorms capable of spinning off tornadoes in Arkansas, Louisiana, Mississippi and Alabama.
The storm forced the cancellation of hundreds of flights, including more than 275 in both Kansas City and St Louis, according to the aviation tracking website FlightAware.
Governors in several states, including Kansas, Kentucky, Arkansas, West Virginia and Virginia, declared states of emergency.
The storm will move offshore by tomorrow night, but bone-chilling arctic air is set to move in behind it. Daytime temperatures over the next two days are predicted to be -23degC to -28degC on average from the Great Plains to the East Coast, according to the weather service.