Five people have reportedly died after a searing heat wave gripped large parts of the United States, tying or breaking previous heat records in dozens of locations across the country's West and Pacific Northwest regions.
High temperatures in Oregon are suspected to have caused four deaths in the Portland area, officials told the Associated Press.
Multnomah County's medical examiner is investigating Oregon's suspected heat-related deaths recorded on Friday, Saturday and Sunday, local time.
According to an email sent by county officials, three deaths involved people over the age of 60. They were 64, 75 and 84 years old.
Heat was also suspected in the death of a 33-year-old man taken to a Portland hospital.
Portland broke daily record temperatures on Friday, Saturday and Sunday and is on track to do so again on Monday with a forecast high of 38.9 degrees Celsius, National Weather Service (NWS) meteorologist Hannah Chandler-Cooley said.
More hot weather is expected through to Tuesday evening.
"We are looking at the potential for breaking more records," she said.
News of the Portland deaths came after a motorcyclist was recorded as having died from heat in California.
A high temperature of 53.3C was recorded on Saturday and Sunday at the state's Death Valley National Park, where a visiting motorcyclist died on Saturday from heat exposure.
Another person was hospitalised, officials say.
They were among six motorcyclists riding through the Badwater Basin area in scorching weather, the park said in a statement.
The other four were treated at the scene.
Emergency medical helicopters were unable to respond because the aircraft cannot fly safely over 48.8C, officials say.
Heat illness and injury are cumulative and can build over the course of a day or days, officials warn.
In San Jose, California, a homeless man died last week from apparent heat-related causes, Mayor Matt Mahan said on X.
More extreme highs are expected, including a a high of around 52.7C in Death Valley on Monday and possibly 54.4C about midweek.
Death Valley is the largest US national park outside Alaska, and is considered one of the most extreme environments in the world.
The hottest temperature ever officially recorded on Earth was 56.67C in July 1913 in Death Valley — though some experts dispute the measurement and say the real record was 54.4C, recorded there in July 2021.
Hundreds of Europeans touring the American West and adventurers from around the US are still drawn to Death Valley National Park, despite the park's heat being named as the motorcyclist's cause of death.
"I was excited it was going to be this hot," Tupelo, Mississippi resident Drew Belt says.
"It's a once in a lifetime opportunity. Kind of like walking on Mars."
Thomas Mrzliek of Basel, Switzerland called the heat "impressive".
"Like a wave that hits when you get out of the car, but it's a very dry heat. So it's not as in Europe."
Park superintendent Mike Reynolds cautioned visitors in a statement that "high heat like this can pose real threats to your health".
The temperatures aren't expected to soar as high as they did during a heat wave in the Pacific Northwest in 2021 which killed an estimated 600 people across Oregon, Washington and western Canada.
However, the extended duration of the heat wave could be problematic because many homes in the region lack air conditioning.
Round-the-clock hot weather keeps people from cooling off sufficiently at night, and it's worse in urban areas where concrete and pavement store heat.
Heat alerts out across the US
Temperatures are expected to continue breaking records in the Pacific Northwest into this week.
More than 146 million people around the US are under heat alerts through to Monday, especially in the western states.
California, Nevada, Arizona, Oregon, Washington and Idaho are under an excessive heat warning, the NWS' highest alert, while parts of the East Coast as well as Alabama and Mississippi are under heat advisories.
In Nevada, Las Vegas set a record high of 48.8C on Sunday and is forecast to hit a record high of 46.1C on Monday.
In north Las Vegas, Alejandro Meza went home from work early after he felt like he was "dragging around in chains" while painting a church exterior.
Touching a metal ladder without gloves was like touching a clothes iron, he said.
His heart rate sped up and he got chills — a sign of heat illness.
"Any time it gets really, really hot out, I'm literally cold," Mr Meza said.
Rare heat advisories were extended even into higher elevations including around Lake Tahoe, Nevada.
The NWS in Reno, Nevada, warned of "major heat risk impacts, even in the mountains".
"Only so many ways we can say it's hot out there," the weather service said in its updated Monday forecast.
"Our long- duration heatwave continues with additional record breaking temperatures a high probability."
Reno is likely to reach 40.5C for the third consecutive day later Monday, which would be the first time that has happened in more than 100 years of record-keeping.
The weather service also said there's a good chance that streak will continue through Thursday.
People flocked to the beaches around Lake Tahoe as the heat wave set in, especially to Sand Harbor State Park.
There, the record high of 33.3C set on Sunday smashed the old record of 31.1C set in 2014.
For the fifth consecutive day, Sand Harbor closed its gates within 90 minutes of opening at 8am because it had reached capacity.
"It's definitely hotter than we are used to," Nevada State Parks spokesperson Tyler Kerver says.
In nearby Sparks, Nevada, security guard Bill DeRushe complained about the heat as he picked up a sandwich at a sports tavern.
"Oh, my God, it's torture out there," Mr DeRushe said.
He explained he had to leave his air-conditioned guard shack to open gates for incoming trucks at a commercial loading dock east of Reno.
He said it's so hot, rattlesnakes, rats and lizards seek shade under his shack.
Feeling sorry for the lizards, he filled a small bottle lid with water.
"I watch them do their little push-ups when they drink from it," he said.
The NWS' forecast a high of 47.2C in Phoenix, Arizona.
The northern California city of Redding hit an all-time high of 48C on Saturday, NWS meteorologist Bryan Jackson said.
"We're expecting it to merely drift east through the early part of next week and basically persist through the week, so we've got a real expansive and extreme heat wave ongoing, and it's expected to continue this week," Mr Jackson said.
The NWS is also warning of increased wildfire risks due to a mix of hot, dry and windy conditions.
Residents of Santa Barbara County in Southern California were ordered late on Saturday to evacuate areas where a fire has scorched more than 5,260 hectares since Friday.
The fire grew to nearly 83 square kilometres early on Monday.
More than 1,000 firefighters were dispatched to control the fire, and areas under evacuation orders included the former Neverland Ranch once owned by the late pop star Michael Jackson.
The global temperature in June was record warm for the 13th straight month and marked the 12th straight month that the world was 1.5C warmer than pre-industrial times, the European climate service Copernicus said.
AP/ABC
