There were nearly 100 cities from Texas to Connecticut that had their hottest October temperature ever recorded on Wednesday.
Some of the records include:
-- Newark, New Jersey: 96 degrees
-- Washington, D.C.: 98 degrees
-- Baltimore: 98 degrees
-- Charlotte, North Carolina: 99 degrees
-- Allentown, Pennsylvania: 93 degrees
The historic heat continues Thursday in the South where temperatures could surpass Wednesday's readings, and some cities could break the records again.
Temperatures are forecast to climb to 100 degrees in Savannah and Memphis.
Click here for tips on how to stay safe in the heat.
(MORE: Heat wave is coming: How to stay safe and prepare an emergency supply kit)But a major fall cooldown is in progress from the Rockies to the Midwest and into the Northeast.
Temperatures dipped by up to 30 to 35 degrees in the Midwest Wednesday as this Autumn cold blast moved east.
In the Northeast, temperatures plunged 30 degrees on Thursday from Wednesday’s highs.
New York City will stay in the cool 50s on Thursday -- a marked change from a record October high of 93 degrees on Wednesday.