A French tourist has died in California's Death Valley after becoming stranded on the side of the road during 46.6C (116F) heat.

Police found 68-year-old Pierre Michel Formosa recently following a brief search, with the National Park service saying he died while trying to seek help in the blistering heat when his car got stuck in mud.

"This is a heartbreaking reminder of how quickly conditions here can turn dangerous," Death Valley National Park Superintendent Mike Reynolds said in a statement.

Soaring temperatures across the United States have caused millions of people to sweat through record heatwaves, leading to dozens of heat-related deaths.

Formosa was driving through Death Valley with his French travelling companion last Monday when their vehicle became stuck in mud on West Side Road.

The pair sought help by walking across the salt flats, before severe heat prevented the 68-year-old from continuing after 1.3 miles, according to the Death Valley National Park.

The travelling companion managed to hail down a nearby driver, before rangers and police found Formosa later that afternoon where he was pronounced dead.

"Death Valley is an extraordinary place, but its heat, distances, and remoteness can be dangerous, regardless of experience," Reynolds said.

"We're grateful to everyone who took part in the search, and our thoughts are with his loved ones."

An extreme heat warning is currently in effect across Death Valley, which brands itself as the "hottest place on Earth", according to its official website, having recorded a global high of 57C (134F) in 1913.

Forecasters at the National Weather Service expected Southern California would experience its "hottest week of summer so far", the bureau said in a recent statement.

Record heatwaves have endangered tourists visiting US landmarks throughout the summer.

At least four hikers died in June while trekking through the Grand Canyon, state authorities reported in Arizona.