Forecasters called for more supercharged temperatures Sunday as a heat wave gripped the Southwest, leaving one man dead and another hospitalized in serious condition in heat-aggravated incidents in this sunbaked city.

Temperatures in Las Vegas shot up to 46 C on Saturday afternoon, two degrees short of a record, while Phoenix baked in 48 C.  Large swaths of California sweltered under extreme heat warnings, which are expected to last into Tuesday night — and maybe even longer.

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Maria Wieser, of Italy, takes a drink of water while sightseeing in Death Valley National Park, where temperatures hit 47 C. (Chris Carlson/Associated Press)

In Death Valley — known as the hottest place on Earth — temps reached about 52 C, according to the National Weather Service. Death Valley's record high of 56.6 C, set nearly a century ago on July 10, 1913, stands as the planet's highest recorded temperature.

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 911 and was taken to the hospital in serious condition.

The oppressive heat has sent more than 40 other people to hospitals in Las Vegas since it arrived Friday, but no life-threatening injuries were reported.

'People may require medical assistance'

"We will probably start to see a rise in calls Sunday and Monday as the event prolongs," Szymanski said in a statement. "People's bodies will be more agitated the longer the event lasts and people may require medical assistance."

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Anita Bouse, of Henderson, Nev., went to Lake Mead Saturday to try and escape the heat in the Las Vegas. (Julie Jacobson/Associated Press)

Elsewhere in Southern California, Palm Springs peaked at 47 C. The strip of gas stations and restaurants between Los Angeles and Las Vegas is known by travellers for the giant thermometer that often notes temperatures in the triple digits.

To make matters worse, National Weather Service meteorologists John Dumas said cooling ocean breezes haven't been travelling far enough inland to fan the region's overheated valleys and deserts.

In Northern California, record-breaking temperatures were recorded in Sacramento, where the high went beyond 41 C.

Cooling stations were set up to shelter the homeless and elderly people who can't 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.

Temperatures are also expected to soar across Utah and into Wyoming and Idaho.

The heat was so punishing that rangers took up positions at trailheads 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.

Heat mass moving to B.C., Alberta

CBC Meteorologist Jay Scotland says the hot air mass sitting over Nevada is expected to move north and will hit the interior B.C. and parts of Alberta on Monday, boosting temperatures in those areas for two days.

The region around Kamloops and Kelowna could near 40 C on Monday, says Scotland.  While areas of Alberta, especially around Grande Prairie, could hit the high 30s.

Meanwhile, southern Alberta, including Calgary and Medicine Hat, will be soaking in hot weather in the mid-30s over the next few days.

With files from the CBC