The coldest air in months is on the way for millions | Weather [Video]

(CNN) — A dramatic pattern shift will bring the chilliest air since spring to millions of people in the central and eastern United States this week, making areas that have struggled so far to shed lingering warmth feel more like November than October.

Extended periods of fall chill have been hard to come by for much of the country since the season began last month. But the combination of an expansive cold front and an upcoming surge of cold, Canadian air, will change that and temperatures could drop to 10 to 15 degrees below average by midweek.

The first aspect of this cooldown — a far-reaching cold front — began over the weekend. This cold front swept from the north-central US and will cross the eastern half of the US by late Monday, ushering in a true autumn chill for some along the way.

The coldest temperatures will remain in the Plains and Midwest Monday, before even chillier air out …