A long-lasting extreme heat wave reached its dangerous crescendo Tuesday, bringing the hottest day in a decade to some major East Coast cities and putting millions of already fatigued Americans at risk.

A life-threatening heat wave has enveloped the East Coast, hitting cities with the worst of the high temperatures on Tuesday before relief moves in later in the week. This is the first major heat wave of the season,

An "extremely dangerous heat wave" is continuing to scorch a huge area of the eastern United States June 23, affecting tens of millions of people.