Meteorologists say a cooldown should start Friday and last at least through the weekend, 'but when you start out more than 10 degrees above normal, it will still feel quite warm.'

On July 5, 61-year-old Hantae Kim set out on the Pacific Crest Trail for a hike. He planned to do only a portion of the 2,650-mile trek, intending to return home to Chula Vista by early morning July 7.

Dangerous heat across the U.S. has affected millions of people, with electric bills expected to increase 7.9% this summer as America fights to keep cool.