Over 90 million Americans on alert for extreme heat

Heat alerts have been issued for 21 states from Washington to Florida on Wednesday, with more than 90 million on alert for extreme weather.

Several wildfires also exploded in the West on Tuesday due to dry conditions and ongoing heat. 

The dangerous heat is just beginning in the West, but it has already claimed the life of a 10-year-old boy who was hiking in Phoenix on Tuesday.

This prolonged heat could be for the record books, and could be one of the worst in 18 years for parts of California.

 A heat advisory has issued for coastal cities, such as Los Angeles and San Francisco, where temperatures could get close to 90 degrees on Wednesday. Inland temperatures could rise into the 110s. 

Dozens of record highs are expected over the next week in the West, even all the way to Seattle and Portland, Oregon.

In the South and Mississippi River Valley, the combination of heat and humidity could push the heat index over 110 degrees.