Approximately 63 million Americans are under a cold weather advisory, and around 11 million are under a freeze warning — mainly in the Gulf States where such low temperatures are rare.

LOS ANGELES - A powerful storm system fueled by an atmospheric river is expected to bring dangerous weather conditions to Southern California beginning Tuesday and lasting through the duration of Christmas week.

Northern California flooding kills 1; storms threaten Bay Area, snow threatens travel. Follow Newsweek's live blog.

Several days of rain and powerful wind gusts are in the forecast this week when a winter storm has already led to evacuation warnings in parts of Los Angeles County settles into Southern California for the holiday.

Winter Storm Warnings remain in effect for the Cascades through late Saturday night into early Sunday, with additional snow expected overnight.

Around 10 million people are under winter weather alerts Monday in the Great Lakes and Northeast regions, where some residents may be waking up to a White Christmas.