Summer's Over: Temperatures Drop Up to 20 Degrees as Fall Chill Arrives

Last week's summerlike warmth has been replaced by the coldest air of the season thus far for a large swath of the Great Lakes and into the interior portions of the Northeast. How cold is it going to get, and when will the chill arrive? We have everything that you need to know right here.

Summer Warmth Replaced by Winter Chill in Northeastern U.S.

The higher terrains of the Great Lakes and the Northeast are under the threat of the first frost or freeze of the season as temperatures plummet to the lowest levels since last spring. Millions of Americans will be left shivering early this week as a mass of cold air dips down from Canada and into some parts of the northern U.S.

The chill will come as quite the shock after last Friday's toasty temperatures. The mercury soared into the mid to upper 80s up and down much of the Interstate 95 corridor to end the work week.

A cold front pushed into the region late Friday, sending temperatures on a downward trajectory that has held. Temperatures were hovering about 10 to 20 degrees lower than Friday's high marks by Sunday afternoon. The clear skies and weakening winds will naturally raise the risk of frost or freeze conditions early Tuesday morning.

Water temperatures across the Great Lakes are still relatively warm. The warmth radiating off these large bodies of water will help to mitigate the risk of an overnight frost along the Great Lakes shorelines. The larger cities in the region will also see temperatures bottom out above frost threat level due to the urban island heat effect.