Old Man Winter has been pretty easy on most of the country so far, but the days of agreeable weather are over in the Midwest, Northern Plains and Northeast — at least for the next few days.

Fourteen states, from Minnesota stretching all the way into North Carolina, were under wind chill advisories, according to the National Weather Service. More than 50 million people across the country could be forced to deal with the wicked cold during the early part of the week.

Cold snap affects more than 52 million Americans 1:11

Temperatures will hover below zero across across many parts of the Dakotas and Minnesota on Monday, according to NWS. With the wind chills factored in, temperatures are expected to drop as low as 20 to 40 degrees below zero in those two states.

Temperatures will remain below zero Fahrenheit across much of the Dakotas and Minnesota on Monday. Wind chill values are expected to drop as low as 20 to 40 degrees below zero in these locations.

Meanwhile, the majority of the country — some 70 percent — was below freezing at 6 a.m. Monday, according to Weather Channel meteorologist Kathryn Prociv. The cold air ushered in the first measurable snowfalls in places like Washington, D.C., Baltimore and New York City.

The northern and central Plains to the mid-Mississippi Valley, Ohio Valley and central Appalachians can expect the next moderate snow, while the east could get a more significant winter storm at the end of the week that may extend through the weekend, according to Weather.com.