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

By Patrick Wingrove NEW YORK (Reuters) -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.

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,