Parts of the United States are expected to see record temperatures on Sunday, with warnings of “dangerous” heat levels into next week across the south-west.
Nearly a third of Americans – about 113 million people – are currently under heat advisories, from Florida to California and up to Washington state.
The country’s National Weather Service (NWS) has urged people not to underestimate the risk to life.
On Saturday, a sweltering 48C was recorded in Phoenix, Arizona.
It means temperatures have hit 43C for 16 days running, which is almost a record.
Mobile clinics there have reported treating homeless people suffering from third-degree burns.
Meanwhile, Death Valley in California – one of the hottest places in the world – is forecast to reach 54C, nearing the hottest temperatures ever reliably recorded on Earth.
The NWS has said that local records could also be set on Sunday in the San Joaquin Valley, Mojave Desert, and Great Basin regions.
Its Saturday-evening update said the temperatures would “pose a health risk and are potentially deadly to anyone without effective cooling and/or adequate hydration”.
About 700 people are estimated to die each year from heat-related causes in the US, according to the Centres for Disease Control and Prevention (CDC).
Air conditioner use in the state has topped its previous record for power consumption as people try to stay cool, while parks, museums and zoos have either closed or shortened their hours.
Hospitals were also seeing heat-related admissions.
“We’re getting a lot of heat-related illness now, a lot of dehydration, heat exhaustion,” said Dr Ashkan Morim, who works in the emergency room at Dignity Health Siena Hospital, outside of Las Vegas.
Overnight temperatures were expected to remain “abnormally warm” in some areas, offering little night-time relief from the heat.
The US heatwave mirrors similar searing conditions in Europe, which forced Greece to close one of its major tourist attractions, the Acropolis, on Friday and Saturday. (BBC)