Sweltering heat wave hits much of the United States

 "The World's Tallest Thermometer" in Baker, California.
California's Death Valley set a new record during Saturday's heat wave, reaching 128 degrees Fahrenheit. | Credit: Robyn Beck / AFP / Getty Images

What happened

Large portions of the West and East coasts were enveloped by extreme heat over the weekend, with deadly temperatures recorded in several cities. California's Death Valley, consistently one of the hottest areas on Earth, set a new record on Saturday, reaching 128 degrees Fahrenheit, while Las Vegas and Arizona saw similar highs. On the other side of the country, heat indexes reached 110 degrees in Maryland and Washington D.C., and in areas throughout the South, including Florida, Georgia and Alabama. 

An excessive heat warning — the National Weather Service's highest alert — was in effect on Sunday for about 36 million people, or about 10% of the population.

Who said what

Climate change caused by humans is "fueling longer and more intensive heat waves, and making dangerously high temperatures more common," NPR said. These types of conditions are "potentially deadly if not taken seriously," said the National Weather Service.

What next?

The "persistent" heat wave is expected to "shatter new records" as temperatures keep climbing in the coming days, NBC News said. In parts of the Pacific Northwest, including Oregon, temperatures "are forecast to stay between 100 to 105 degrees through Tuesday night," said NPR. Nationwide, a total of 40 million people are expected to swelter in temperatures of more than 100 degrees over the next week.