Story highlights Over 120 million people will see temperatures above 95 over the next week

The heat index could reach 115 for places like Chicago, Kansas City and Minneapolis

(CNN) Nearly 60 million people across the nation's midsection are under some type of heat watch, warning or advisory from the National Weather Service as the worst heat wave of 2018 arrives.

That number will only increase this weekend as the axis of extreme temperatures shifts toward the big cities of the Northeast.

Over 120 million people in the United States will see the temperature climb above 95 degrees Fahrenheit during the next week.

On Thursday, the extreme heat can be found over the Rockies and Central Plains, with Denver expecting a record high of 103 degrees, the city's hottest day since it tied the all-time Denver maximum of 105 in late June 2012.

Major heat for Midwest

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