Dangerous heat wave to blanket 120 million people across US

On Thursday, the extreme heat can be found over the Rockies and Central Plains, with Denver expecting a record high of 39.5 degreesCelsius, the city's hottest day since 2012.

The Midwest will see its hottest days on Friday and Saturday as the temperature can reach 46 degree Celsius. Excessive-heat watches and warnings are posted for these locations, where "high temperatures and high humidity will combine to create a dangerous situation in which heat illnesses are possible," according to the National Weather Service.