WHO warns about 'new reality' of killer heat waves as scorching temperatures continue around the world

Heat records are being shattered all over the world, and scientists say there's a good chance 2023 will go down as the hottest year on record, besting measurements going back to the middle of the 19th century.

As heat waves intensified across southern and eastern Europe, Asia and much of the United States on Tuesday, the World Meteorological Organization (WMO) warned of an increased risk of deaths due to the extreme weather.

"Temperatures in North America, Asia, and across North Africa and the Mediterranean will be above 40 C for a prolonged number of days this week as the heat wave intensifies," the WMO said.

Overnight minimum temperatures were also expected to reach new highs, the organization said, increasing the risk of heart attacks and deaths.

While most of the focus is on daytime maximum temperatures, the WMO says "it is the overnight temperatures which have the biggest health risks, especially for vulnerable populations."

Human-caused climate change from the burning of coal, oil and natural gas is making the world hotter and is being amplified by the naturally occurring El Niño weather phenomenon.

But the current El Niño only started a few months ago and is still weak to moderate and isn't expected to peak until winter.

Preliminary figures suggest the global average temperature last month set a new June record, according to the European Union's Copernicus Climate Change Service.

The World Health Organization's regional director for Europe, Hans Henri P. Kluge, said the world must look ahead while adapting to the "new reality" of killer heat waves and other extreme weather.

"There is a desperate and urgent need for regional and global action to effectively tackle the climate crisis, which poses an existential threat to the human race," he said.

A massive heat dome parked over the southern and western United States is keeping tens of millions of Americans under extreme heat advisories.

The city of Phoenix, Ariz., on Tuesday exceeded 43 C for the 19th day in a row, breaking its all-time record of 18 straight days over 43.

Arizona's largest utility reported that electricity demand was at an all-time high of 8,191 megawatts (MW) on July 15, mirroring trends in Texas. Central Texas, an area stretching from San Antonio north to Dallas, is forecast to reach 40.5 C or higher over the next two days.

The hottest spot in the U.S. on Tuesday is expected to be Death Valley, Calif., where temperatures at the visitors centre at Death Valley National Park are expected to reach 50 C.