Western US states are currently experiencing with temperatures threatening to break the all-time high recorded on Earth.
In Phoenix, Arizona, the mercury hit 47C (116F) on Friday, and in the desert of Death Valley, California, the thermometer approached 51C.
The heat wave is expected to last through the weekend.
Cities in the region are opening cooling centres and officials fear the heat could delay air travel.
“This is the hottest time of the year, but the temperatures that we’ll be looking at for Friday through Sunday, they’ll be toward the top,” said weather service meteorologist Mark O’Malley. “It’s going to be baking hot across much of the entire west.”
The heat is the result of a high-pressure system brought on by a shift in the jet stream, the high-altitude air current that dictates weather patterns. The jet stream has been more erratic in the past few years.
While people have been hospitalised due to heat effects, tragically, at least 19 Arizona firefighters have been killed battling a wildfire in central Arizona.
They died while fighting the blaze threatening the town of Yarnell, about 80 miles (130km) north-west of Phoenix.
The fire was started by lightning on Friday and spread rapidly amid high heat, low humidity and strong winds. At least 200 homes were burned.