Extreme weather conditions from coast to coast put more than half the U.S. in the path of rough conditions. Storms across the nation's eastern half forced airlines to cancel more than 3,000 flights nationwide Monday. Many schools closed early in the mid-Atlantic states, where high winds and tornadoes were in the forecast. Blizzards buried parts of Michigan, Wisconsin and Minnesota while torrential rains flooded homes and washed out roads in Hawaii. California is dealing with unusually high temperatures for this time of year. Areas near San Francisco could see temperatures in the high 80s.

Tens of thousands of people are entering their sixth day with no electricity as the Carolinas and Virginia prepare for a significant winter storm that could bring more snowfall than some parts of North Carolina have seen in years. The National Weather Service says arctic air moving into the Southeast will cause already frigid temperatures to plummet into the teens Friday night in cities like Nashville, Tennessee. With another wave of dangerous cold heading for the U.S. South, experts say the risk of hypothermia heightens for people in parts of Mississippi and Tennessee trapped at home without power in subfreezing temperatures.