A man died and another was in hospital in a serious condition as a heatwave blistered parts of the US.
Forecasters said temperatures in Las Vegas shot up to 46C (115F) yesterday, two degrees short of the city's all-time record.
Phoenix hit 48.3C (119F) by mid-afternoon, breaking the record for June 29 that was set in 1994.
And large areas of California sweltered under extreme heat warnings, which are expected to last into Tuesday night - and maybe even longer.
The forecast for Death Valley in California predicted 53.3C (128F) yesterday, but it was a few degrees shy of that, according to unofficial reports from the National Weather Service.
Death Valley's record high of 56.6C (134F) set a century ago, stands as the highest temperature ever recorded on Earth.
Las Vegas fire and rescue spokesman Tim Szymanski said paramedics responded to a home without air conditioning and found an elderly man dead.
He said while the man had medical issues, paramedics thought the heat worsened his condition.
Paramedics said another elderly man suffered a heat stroke when the air conditioner in his car went out for several hours while he was on a long road trip.
He stopped in Las Vegas, called for help and was taken to the hospital in serious condition.
The heat wave has sent more than 40 other people to hospitals in Las Vegas since it arrived on Friday, but no life-threatening injuries were reported.
"We will probably start to see a rise in calls Sunday and Monday as the event prolongs," Mr Szymanski said.
"People's bodies will be more agitated the longer the event lasts and people may require medical assistance."
About 100 miles south in Baker, the temperature peaked at an unofficial 47.22C (117F) in the road tripper's oasis in the Mojave Desert on Interstate 15.
The strip of gas stations and restaurants between Los Angeles and Las Vegas is known by travellers for the giant thermometer that often records temperatures in the triple digits.
Elsewhere in Southern California, Palm Springs peaked at 50C (122F).
National Weather Service meteorologist John Dumas said cooling ocean breezes have not been travelling far enough inland overnight to fan the region's overheated valleys and deserts.
Cooling stations were set up to shelter the homeless and elderly people who cannot afford to run their air conditioners. In Phoenix, Joe Arpaio, the famously hard-nosed sheriff who runs a tent jail, planned to distribute ice cream and cold towels to inmates this weekend.
Officials said personnel were added to the Border Patrol's search-and-rescue unit because of the danger to people trying to slip across the Mexican border.
At least seven people have been found dead in the last week in Arizona after falling victim to the brutal desert heat.
The heat was so punishing that rangers took up positions at trails at Lake Mead in Nevada to persuade people not to hike.
Zookeepers in Phoenix hosed down the elephants and fed tigers frozen fish snacks. Dogs were at risk of burning their paws on scorched pavement, and airlines kept close watch on the heat for fear that it could cause flights to be delayed.