A major storm is moving from west to east Saturday, leaving roads especially dangerous as travelers head home after the holidays.
The main impacts over the next 24 hours will be in the Plains and the upper Midwest. Winter weather advisories are in effect for cities including Denver and Minneapolis.
Freezing rain hit the Twin Cities Saturday, and police in Minnesota are warning drivers to stay home as dangerous ice covers roadways.
Statewide, there were 357 crashes between 5 a.m. and 10 a.m. Saturday, according to the Minnesota State Patrol.
Temperatures were starting to warm up in the Twin Cities by Saturday afternoon.
In Denver, the blowing and drifting snow continues to cause limited visibility for drivers, which could wreak havoc on roadways.
By Sunday morning, heavy snow and strong winds will be hitting much of North Dakota, South Dakota, Nebraska and northern Minnesota. Some areas could get more than a foot of snow.
Conditions will be rainy and milder in Minneapolis, the Great Lakes and Chicago.
Airlines have issued weather waivers for passengers traveling through the Midwest and upper Midwest airports Saturday and Sunday.
By Sunday night, snow and icy conditions will persist in the upper Midwest with areas of heavy rain, thunderstorms and possible flash flooding in the South.
By that point the storm will be taking aim on the Northeast, bringing rain and a wintry mix.
By the Monday morning commute, rain will be falling across much of the Northeast with heavy downpours possible in some spots.
Freezing rain will be a concern from upstate New York into parts of New England.
But this storm is forecast to clear out Tuesday morning in time for New Year's Eve.
ABC News' Mina Kaji contributed to this report.