Roughly 130 million people in the US are under threat from the weekend into next week from a long-running heat wave that has already broken records with dangerously high temperatures, forecasters said.

Oppressive heat and humidity could team up to spike temperatures above 38C in parts of the Pacific North-west, the Mid-Atlantic and the North-east, said Jacob Asherman, a meteorologist with the National Weather Service.

In Oregon, records could be broken in cities including Eugene, Portland and Salem, Mr Asherman said.

Dozens of other records throughout America could fall, Mr Asherman said, causing millions to seek relief from the blanket of heat in cooling centres from Bullhead City, Arizona, to Norfolk, Virginia.

Corinne Dickey, of Portland, Ore., cools off under a mister
A potentially record-setting heatwave is spreading across the western US (AP)

He added: “Certainly a pretty anomalous event that we’re expecting here, which looks like it will continue through at least midweek.”

At the Waterfront Blues Festival in Portland, Oregon, music fans dealt with heat on Friday by drinking cold water, seeking refuge in the shade or freshening up under water misters.

Also on Friday, a new heat record for the day was set in California’s Death Valley – one of the hottest places on Earth. The previous high was shattered by five degrees Fahrenheit, with the mercury climbing to 127F (52.8C). The old mark of 122F (50C) was last tied in 2013.

More extreme highs are in the near forecast, including 53.8C for Sunday at Furnace Creek in Death Valley National Park, and then around 54.4C through until Wednesday.

The hottest temperature ever officially recorded on Earth was 134F (56.67C) in Death Valley in July 1913, though some experts dispute that measurement and say the real record was 130F (54.4C) recorded there in July 2021.

There was also a record high for the date of 118F (47.7C) in Phoenix, where highs of 115F (46.1C) or hotter were forecast through until Wednesday.

In Needles, California, where the National Weather Service has records dating to 1888, the high of 50C edged the old mark of 49.4C set in 2007. It was 51.1C in Palm Springs, California.

The worst was yet to come across much of the West, with temperatures between 8C and 16C higher than average into next week, the National Weather Service said.

The Eastern US also was bracing for more hot temperatures. Baltimore and others parts of Maryland were under an excessive heat warning, as heat index values could climb to 43C, forecasters said.

With an American flag reflected in the Willamette River, people sit on their paddle boards and listen to the music at the Waterfront Blues Festival
People have been warned to take care (AP)

“Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbours,” said a National Weather Service advisory for the Baltimore area.

“Young children and pets should never be left unattended in vehicles under any circumstances.”

In Arizona’s Maricopa County, which encompasses Phoenix, there have been at least 13 confirmed heat-related deaths this year, along with more than 160 other suspected heat deaths are still under investigation, according to the county’s most recent report.

That does not include the death of a 10-year-old boy earlier this week in Phoenix who suffered a “heat-related medical event” while hiking with family at South Mountain Park and Preserve, according to police.