The first major heat wave of the year broke through early summer temperatures in the western United States before easing slightly on Friday.
Millions of people in California, Nevada, Arizona, New Mexico and Texas are under extreme heat warnings this week.
While the region remains hotter, climate change exacerbated by human activity has led to more extreme weather and the current heat wave is historically early.
Las Vegas recorded 111 degrees Fahrenheit (44 degrees Celsius) on Thursday, marking the previous record high of the year.
“The past few days have been warm,” the National Weather Service said in a long list of places where daily records fell.
Among them, the worst scorching Death Valley desert reached 122F.
Las Vegas remains under an extreme heat warning until Saturday, where residents have turned libraries into cooling stations to escape the furnace, and some events have forced people to go indoors.
At a Trump rally in Arizona, nearly a dozen people were taken to hospitals with heat exhaustion, fire officials told a local ABC affiliate.
Hiking on the popular Camelback Mountain and Piestewa Peaks in the state capital, Phoenix, was banned due to the heat.
“With temperatures nearing 110 degrees, this is not a day for hiking,” the Phoenix Fire Department posted on Facebook.
Coastal areas are largely spared.
But in an ominous sign of the summer months to come, several small wildfires broke out across California.
Firefighters have burned 3,600 acres (more than 1,450 hectares) of the heavily agricultural Central Valley, about 150 miles northwest of Los Angeles.
After nearly 20 years of drought and a slowly drying climate, California has seen an alarming number of destructive fires in recent years.
Wildfires are a natural and necessary part of the life cycle of the region.
But climate change, caused by humanity’s burning of fossil fuels that inject greenhouse gases into the atmosphere, makes them bigger, hotter and more unpredictable.
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