At least 134 people have died suddenly since Friday in the Vancouver area, according to figures released by the city police department and the Royal Canadian Mounted police.
The Vancouver Police Department alone said it had responded to more than 65 sudden deaths since Friday, with the vast majority "related to the heat."
The deaths came as Canada set a new all-time high temperature record for a third day in a row Tuesday, reaching 121 degrees Fahrenheit (49.5 degrees Celsius) in Lytton, British Columbia, about 155 miles (250 kilometres) east of Vancouver, the country's weather service, Environment Canada, reported.
"Vancouver has never experienced heat like this, and sadly dozens of people are dying because of it," police sergeant Steve Addison said.
Other local municipalities have said they too have responded to many sudden death calls, but have yet to release tolls.
Climate change is causing record-setting temperatures to become more frequent. Globally, the decade to 2019 was the hottest recorded, and the five hottest years have all occurred within the last five years.
The scorching heat stretching from the US state of Oregon to Canada's Arctic territories has been blamed on a high-pressure ridge trapping warm air in the region.
Temperatures in the US Pacific Northwest cities of Portland, Oregon and Seattle, Washington reached levels not seen since record-keeping began in the 1940s: 115 degrees Fahrenheit in Portland and 108 in Seattle Monday, according to the National Weather Service.
Vancouver on the Pacific coast has for several days recorded temperatures above 86 degrees Fahrenheit (or almost 20 degrees above seasonal norms). Inland along the Fraser River delta, due to high humidity, climatologists said it felt like 111 degrees Fahrenheit on Tuesday.
The chief coroner for the province of British Columbia, which includes Vancouver, said that it had "experienced a significant increase in deaths reported where it is suspected that extreme heat has been contributory."
The service said in a statement it recorded 233 deaths between Friday and Monday, compared to 130 on average.
'Hottest week ever'
"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," British Columbia Premier John Horgan told a news conference.
"How we get through this extraordinary time is by hanging together," he said.
He urged "checking 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 Northwest Territories, saying the "prolonged, dangerous and historic heatwave will persist through this week."
The US National Weather Service issued a similar warning, urging people to "stay in air-conditioned buildings, avoid strenuous outdoor activities, drink plenty of water, and check on family members/neighbors."
The heatwave has forced schools and Covid-19 vaccination centers to close in the Vancouver area, while officials set up temporary water fountains and misting stations on street corners.
Stores 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.
Cities across the western United States and Canada opened emergency cooling centers and outreach workers handed out bottles of water and hats.
In Eugene in Oregon, organizers were forced to adjust the final day of the US Olympic track and field trials, moving afternoon events to the evening.
The extreme heat, combined with intense drought, also created the perfect conditions for several fires to break out over the weekend, and one blaze on the California-Oregon border had already burned some 1,500 acres (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.