Dangerous heat wave to grip most of the nation for July 4 celebrations

Dangerous heat wave to grip most of the nation for July 4 celebrations

A massive heat dome is settling over the eastern half of the country, triggering the first major heat wave of the summer, just ahead of the July 4 holiday. While temperatures may peak before July 4 itself, millions across the country will still experience triple-digit air temperatures or heat index values as they celebrate America's 250th birthday.