An arctic blast will send temperatures across the United States plummeting as bitterly cold air that originated in Siberia will arrive from Canada by week’s end, bringing with it dangerously cold wind chills for millions of Americans.

The harshest week of winter thus far has begun, kicking off with several inches of snow in much of Massachusetts. Overnight, a widespread 4-8 inches of snow fell across most of southern New England. Slightly lower amounts fell over extreme southeastern Massachusetts.

A new blast of Arctic air sweeping from north to south will bring bone-chilling temperatures to millions of Americans this weekend and next week.

Dangerously cold weather will put much of the United States into a deep freeze over the weekend as temperatures are expected to plunge by up to 40 degrees behind an Arctic air mass.

However, a deep freeze, thanks to the polar vortex dipping down from Siberia, is about to bring even harsher arctic blast to nearly 300 million Americans starting this weekend. Maps show where and when the cold front will arrive.