A digital billboard displays the temperature in downtown Phoenix, July 17, 2023. (PHOTO / AP)

PHOENIX – Asia, Europe and the United States baked under extreme heat on Monday as global temperatures soared toward alarming highs.

The United States was scorched by record-setting heat in the West and South, lashed with flood-triggering rain in the Northeast, and choked by wildfire smoke in the Midwest.

A heat dome parked over the western United States pushed the temperature in California's Death Valley desert to 53 C on Sunday, among the highest temperatures recorded on Earth in the past 90 years.

Phoenix hit 45.5 C on Monday, matching a historic record of 18 straight days over 43 C with the forecast showing the record likely to extend for at least another week.

The US heatwave coincided with extreme temperatures elsewhere throughout the Northern Hemisphere.

Wildfires in Europe raged ahead of a second heat wave in two weeks that was set to send temperatures as high as 48C, while authorities in Italy and France issued heat-related health warnings

Wildfires in Europe raged ahead of a second heat wave in two weeks that was set to send temperatures as high as 48 C, while authorities in Italy and France issued heat-related health warnings.

Even in Phoenix, accustomed to hot weather, the prolonged bout of extreme heat is testing people and worrying officials. The international charitable organization Salvation Army has opened 11 cooling centers and sent out a mobile unit to deliver relief to homeless people who have difficulty reaching the sites.

"Extreme heat is Arizona's natural disaster. So for the Salvation Army, this is a disaster response," said Scott Johnson, a spokesperson for the organization in the US Southwest.

The heat killed 425 people in the Phoenix-area's Maricopa County last year, so the Salvation Army mobile unit distributes urgently needed cold water, hats, sunscreen and hygiene kits to those in need.

"It feels like you're inside of a dryer, the dryer at the laundromat. And it's suffocating," said Cristina Hill, an unhoused woman who benefited from the outreach on Monday and said she suffered a heat stroke last year. "I cry all the time. I yell at the heat."

Another unhoused woman, Maritza Villegas, said she has gotten shaky and jittery from the heat, which provoked dry heaves.

"This means a whole lot – the world – because without water I'd be in the hospital right now," Villegas said of the assistance.

Scientists have long warned that climate change, caused by CO2 emissions from burning fossil fuels, will make heatwaves more frequent, severe and deadly. They say governments need to take drastic actions to reduce omissions to prevent climate catastrophe.

READ MORE: Heat baking US Southwest, expected to get worse

The European Union's Copernicus Climate Change Service says 2022 and 2021 were the continent's hottest summers on record.

European heatwave unrelenting

An unrelenting heatwave continued in Europe as well.

Italy's health ministry on Monday issued red weather alerts – signaling a possible health threat for anyone exposed to the heat – for 20 of the country's 27 main cities on Tuesday, with the number expected to rise to 23 on Wednesday.

France's public health agency said the current stretch of hot weather would probably hospitalize or kill "many" people, as heat waves have done almost every summer since 2015. The World Meteorological Organization said the extreme heat and rainfall was expected to extend into August.

"In many parts of the world, today is predicted to be the hottest day on record," tweeted Tedros Adhanom Ghebreyesus, director-general of the World Health Organisation.

"The #ClimateCrisis is not a warning. It's happening. I urge world leaders to ACT now."

ALSO READ: Southern Europe braces for 'heat storm', health alerts issued

As many as 61,000 people may have died in Europe during heatwaves last summer, with a repetition feared this season.

"My worry is really health – the health of vulnerable people who live just below the rooftops of houses which are not prepared for such high temperatures," said Robert Vautard, a climate scientist and director of France's Pierre-Simon Laplace Institute. "That could create a lot of deaths."