Reacting to the all-time high temperatures in the country, Canadian Prime Minister Justin Trudeau said, "The temperatures recorded this week are unprecedented -- lives have been lost and the risk of wildfires is at a dangerously high level."
Meanwhile, US President Joe Biden told a virtual meeting with governors from western states that "the threat of western wildfires this year is as severe as it's ever been."
"This is one of the most extreme heat waves that we have seen on Earth, in many years, anywhere, in terms of the deviation from the typical conditions in this particular part of the world," said Daniel Swain, a climate expert at UCLA, noting that temperature records are rarely broken by "more than a degree."
"In this case, those records were obliterated," he said. "It's really the magnitude and the persistence of this one that is just genuinely shocking."
Canada set an all-time record on Tuesday. In Oregon, temperatures were higher than the maximum recorded in Las Vegas, in the middle of the Nevada desert.
Seattle, Portland and many other cities broke all-time heat records, with temperatures in some places reaching above 115 degrees Fahrenheit (46 Celsius).
And all this in a region with a normally temperate climate at this time of the year.
The phenomenon causing the scorching heat is called a "heat dome." Hot air is trapped by high-pressure fronts, and as it is pushed back to the ground, it heats up even more.
"It's sort of like a bicycle pump," said Philip Mote, professor of atmospheric science at Oregon State University. "If you compress air into a bike tire, it warms the air."
The condition also prevents clouds from forming, allowing for more radiation from the sun to hit the ground.
Such conditions are not unheard of: "The pattern was similar to how we always get our heat waves," Karin Bumbaco, a climatologist at the University of Washington, told AFP. "We've seen that pattern before, but it was just much stronger than usual."
The very high temperatures or humidity conditions posed an elevated risk of heatstroke or heat exhaustion.
With agency inputs
Subscribe to Mint Newsletters
* Enter a valid email
* Thank you for subscribing to our newsletter.
Never miss a story! Stay connected and informed with Mint.
our App Now!!