Doctors have warned roads could burn people and 200 temperature records are set to be broken as the west coast reaches 127 degrees Fahrenheit (52 degrees celsius).
Dozens of daily high records have already been topped this week, including 101 (38C) in Denver and 104 (40C) in Helena, Montana, and other cities, such as Salt Lake City, Utah, set new high marks by more than five degrees.
And there is no immediate end in sight with triple digit temperatures in store for western states through the weekend.
More than 200 million people in the US will experience temperatures of more than 90 (32C) in the next week, while 40 million will deal with temperatures topping 100 (37C).
And in some places in the southwest desert, scorching temperatures could reportedly reach between 125 and 127 (51C to 52C) , threatening the hottest ever mark for the month of June.
Officials have warned people in Arizona and Nevada to be careful of hot roadways and pavements in the sizzling temperatures.
The high pressure weather system will see heat warnings in California, where it could hit 117 (47C) degrees in Palm Springs later this week, as well as Montana and Wyoming.
The National Weather Service’s excessive heat warnings will stay in place for Arizona, Utah, Nevada and parts of California through the weekend.
And AccuWeather forecasters have called it a “rare, dangerous and deadly” event.
In southwest states the issue of burns from overheated surfaces is increasing every year, according to burns specialists.
Dr Kevin Foster of the Arizona Burn Center in Phoenix, Arizona, said 104 people were admitted in June, July and August 2020 with serious burn injuries due to contact with scorching surfaces, with seven deaths.
“It doesn’t take much time to get a full thickness or third degree burn when exposed to hot pavement,” Dr Foster told a briefing.
“Because if you look at hot pavement or asphalt at two o’clock in the afternoon in direct sunlight, the temperature is usually somewhere around 170 to 180 degrees Fahrenheit (76C to 82C).”
He added that said severe burns from contact with hot surfaces rose 49 per cent in 2020 from 2019, hitting their highest ever number since they began tracking them in 2000.
“Almost all of those patients required surgery, which included for burn excision and skin grafting,” he said.
Doctors at the Lions Burn Care Center at the University Medical Center in Las Begas, Nevada, say that injuries caused by falling onto the ground are so common during high temperatures that they call the summer there “pavement burn season.”
“It is a significant part of our population,” said Dr Syed Saquib.
Pavement burns are often severe and require longer hospital stays and a greater need for surgery, according to a study published by Dr Saquib earlier this year.
This is because often the people who suffer injuries of this kind are unable to get up off the scorching ground because they have collapsed from dehydration, heat stroke, or because they are intoxicated.
In Nevada, officials say they see cases spiking when outdoor temperatures go past 95 degrees Fahrenheit (35C).
Authorities say that the elderly should stay indoors during the hottest hours of the day.
They also warn people to be careful around metal door handles, seat belt buckles, leather car seats, poolside concrete and playground equipment.
The Associated Press contributed to this report