More than 160 million Americans are under the highest level of extreme heat alerts during a wave of above-average temperatures.

Tens of millions of people in major cities across the U.S. Northeast are facing record high temperatures on Tuesday on what was expected to be the worst day of an oppressive heat wave that has spread over much of the country since late last week.

Temps are soaring in cities across the Atlantic coast, where some cities are reaching 100 degrees with heat indexes approaching 110 degrees.