The Canadian province of British Columbia nearly doubled its average number of deaths as temperatures hit a high of 49.5°C, breaking the country's record for a third consecutive day.
At least 486 sudden deaths were reported over five days, nearly three times the usual number that would occur in the province over that period, the British Columbia Coroners Service said Wednesday.
The Vancouver Police Department said it responded to more than 65 sudden deaths since Friday, with by far most being related to the heat.
Lytton, British Columbia – about 250 kilometres north-east of Vancouver – reached 49.5°C, reported the country's weather service, Environment Canada.
“Vancouver has never experienced heat like this and sadly dozens of people are dying because of it,” police sergeant Steve Addison said.
Other municipalities said they also responded to many sudden death calls but have yet to release details.
The heatwave has scorched crops across the Prairies, where farmers grow much of the world's wheat and canola, driven up natural gas prices in the fourth-largest global producer, and closed schools.
Some Vancouver residents said they had never experienced such temperatures before.
“It's never this bad. I've never seen anything like this,” said one resident, who gave her name as Rosa.
“I hope it never becomes like this ever again. This is too much.”
Others said some residents were more vulnerable to the heat than others.
“I feel for those people, whether they're the elderly demographic or people who live on the Downtown Eastside of Vancouver who don't have a cool spot to live or sleep,” said another resident, Graham Griedger.
For several days, Vancouver has recorded temperatures almost 20 degrees above seasonal norms.
“We are in the midst of the hottest week British Columbians have ever experienced, and there are consequences to that, disastrous consequences for families and for communities,” said British Columbia Premier John Horgan.
He called on residents to check up on "those people we know might be at risk, making sure we have cold compresses in the fridge or we're staying in the coolest part of our homes, and making sure that we're taking steps to get through this heatwave”.
Environment Canada has issued alerts for British Columbia, Alberta, and parts of Saskatchewan, Manitoba, Yukon and the North-west Territories, saying the “prolonged, dangerous and historic heatwave will persist through this week”.
The heatwave has forced schools and Covid-19 vaccination centres in the Vancouver area to close. Officials have set up temporary water fountains and misting stations on street corners.
Shops quickly sold out of portable air conditioners and fans, so several people without cooling at home told AFP they hunkered down in their air-conditioned cars or underground parking garages at night.
The scorching heat stretching from the US state of Oregon to Canada's Arctic territories has been blamed on a high-pressure ridge, which is trapping warm air in the region.
Temperatures in the US Pacific North-west cities of Portland and Seattle reached levels not seen since record-keeping began in the 1940s: 46.1°C in Portland and 42°C in Seattle on Monday, the National Weather Service said.
The state of Oregon reported 63 deaths linked to the heatwave. Multnomah County, which includes Portland, reported 45 of those deaths since Friday, with the county medical examiner saying hyperthermia was the preliminary cause.
"This was a true health crisis that has underscored how deadly an extreme heat wave can be," Multnomah County Health Officer Dr Jennifer Vines said.
"As our summers continue to get warmer, I suspect we will face this kind of event again."
Cities across the western US and Canada opened emergency cooling centres and outreach workers handed out hats and bottles of water.
The extreme heat, combined with intense drought, also created the perfect conditions for fires to break out at the weekend. One blaze on the California-Oregon border burnt about 600 hectares by Monday morning.
“Dubai would be cooler than what we're seeing now,” David Phillips, a senior climatologist for Environment Canada, told AFP on Monday.
Climate change is causing record-setting temperatures to become more frequent. Globally, the decade to 2019 was the hottest on record. The past five years have been the world's hottest.