Iowa ? Weekend storms in the nation’s northern half knocked out power to thousands of customers Sunday and created nightmarish conditions for holiday travelers coast to coast on the first official day of winter.

Gusty winds in the Midwest, where wind chills dipped to minus 30 or lower, produced whiteout conditions that contributed to at least three vehicle pileups in Wisconsin and Michigan.

And blizzard warnings were issued for parts of Maine, where up to 24 inches of snow was expected. Forecasters warned that strong wind could create whiteout conditions and deep drifts.

“This is a classic nor’easter,” said meteorologist John Cannon. “It’s got all the features.”

Parts of Iowa and Illinois were under blizzard warnings. Power was knocked out to more than 35,000 customers Sunday in Illinois shortly after being restored to most who had lost it after a storm last week, utilities said.