Heat dome's triple-digit temperatures fry US south-west

Two weeks before summer even officially starts, excessive heat warnings were in effect across parts of California, Nevada, Arizona and Texas. Forecasters see no relief for several more days.

Temperatures were predicted on Wednesday to reach 109F (42.7C) in Phoenix, 107F in Las Vegas, 110F in Palm Springs and 119F Death Valley, California.

By end of the day, the National Weather Service (NWS) says Americans in the region may experience "easily their hottest" weather since last September, according to the Associated Press.

The mercury is soaring as a result of a heat dome, an area of high pressure where hot air is pushed down and trapped, causing temperatures to soar over large areas.

Temperatures will be 20-30 degrees Fahrenheit above average for this time of year, according to the NWS.

Heat dome brings scorching temperatures to parts of US

In Arizona, the hottest big city in the US, firefighters have placed at least one heat-stroke victim inside human-sized immersion bags filled with ice cubes to lower the patient's body temperature on the way to hospital.

All Phoenix fire department vehicles are being equipped with the bags.

There were 645 heat-related deaths last year in Maricopa County, where Phoenix is located.

The city is also opening two overnight cooling stations this week for the first time.

The NWS predicted temperatures could reach 111F at the Grand Canyon and advised that hikers use extra caution when outdoors for an extended period of time at lower elevations.

The excessive heat also led to Arizona officials closing popular trails at Camelback Mountain and Piestewa Peak.

Forecasters predict temperatures in Las Vegas could reach 112F on Thursday.

Across the state, temperatures were expected to range from 102F to 115F.

The triple-digit heat is a particular danger for unhoused individuals, advocates said, which has led to a growing demand for temperature-controlled shelter.

Central Arizona Shelter Services (CASS) has the capacity to house 600 people who are experiencing homelessness when temperatures reach these levels, its chief executive, Phillip Scharf, told BBC News on Wednesday.

And that need is noticable at the moment, he said.

"We have an increase in people looking for services and a change in the behaviour because it’s oppressively hot outside,” Mr Scarf said.

Not only are people looking for a place to sleep but they are also looking for a place to stay during the day as the heat reaches record temperatures, he said.

CASS, the largest single shelter in the state of Arizona, offers Phoenix-area residents shelter, water, food and more.

It's a service that is much-needed, as unhoused and low-income residents make up the largest population of heat-related deaths in Maricopa County - where Phoenix is located.

In Texas, San Angelo reached 111F on Tuesday, tying with the fifth hottest temperature ever recorded in that city, according to the local NWS office.

The heat warnings were expected to run until the end of Friday.

The extreme temperatures are forecast to spread north by the weekend to the Pacific north-west.

-bbc