From the Mississippi Valley to the east coast more than 150 million are under heat alerts. Scorching temperatures are hitting people in some of the largest U.S. cities. In D.C., the Washington monument remains closed according to a National Parks spokesperson.

In major cities such as Washington, D.C., Baltimore, Philadelphia and New York, the temperature was forecast to approach 100 degrees through at least June 24, which would mark the first time in many decades that triple-digit heat has been experienced in June, AccuWeather said.