Record temperatures are baking the Pacific northwest on both sides of the border, melting power cables, causing blackouts, and producing notably warmer nighttime temperatures that a Canadian expert says are nothing less than a “fingerprint of climate change.”

Simon Donner, a professor in the University of British Columbia’s geography department, says average daytime highs for this time of the year in the province are usually around 22 degrees Celsius, but the mercury is expected to hit 34 this week. But, more important, are the unusually high night-time readings – two degrees higher than the usual 24-degree C average temperature in the province.

“That’s how unusual this is,” he says. “It’s going to be warmer overnight than it usually is in the middle of the day,” adding, warming nighttime temperatures are “like a fingerprint of climate change. (And) this is exactly a specific sort of prediction that scientists have been making. That we would have warmer nights.”

He calls the heat wave unprecedented because of its magnitude and duration.

Environment Canada has warned that the heat wave won’t lift for days, although parts of BC and Yukon could see some relief sooner. However, 60 temperature records fell on Sunday in BC, including in the village of Lytton, where the mercury reached 46.6 degrees C – breaking the all-time Canadian high of 45 C, set in Saskatchewan in 1937.

US

Meanwhile, the unprecedented Northwest US heat wave that has slammed Seattle and Portland, Oregon, moved inland Tuesday — prompting a electrical utility in Spokane, Washington, to warn that people will face more rolling blackouts amid heavy power demand.

The intense weather that gave Seattle and Portland consecutive days of record high temperatures far exceeding 100 degrees F (37.7 C) was expected to ease in those cities, but inland Spokane was likely to surpass Monday’s high temperature – a record-tying 105 F (40.6 C) – and reach 110 F (43.3C), which would be an all-time record.

Temperatures in other eastern Washington and Oregon communities were expected to reach about 115 degrees F (45.6 C) a day after Seattle and Portland shattered all-time heat records.

Seattle hit 108 degrees F (42 C) by Monday evening — well above Sunday’s all-time high of 104 F (40 C). Portland, Oregon, reached 116 F (46.6 C) after hitting records of 108 F (42 C) on Saturday and 112 F (44 C) on Sunday.

The temperatures have been unheard of in a region better known for rain, and where June has historically been referred to as “Juneuary” for its cool drizzle. Seattle’s average high temperature in June is around 70 F (21.1 C), and fewer than half of the city’s residents have air conditioning, according to US Census data.

The heat forced schools and businesses on Monday to close to protect workers and guests, including some places like outdoor pools and ice cream shops where people seek relief from the heat. COVID-19 testing sites and mobile vaccination units were out of service as well.

In Portland, light rail and streetcar service was suspended as power cables melted and electricity demand spiked.

Heat-related expansion caused road pavement to buckle or pop loose in many areas, including a Seattle highway. Workers in tanker trucks hosed down drawbridges with water twice daily prevent the steel from expanding in the heat and interfering with their opening and closing mechanisms.

The heat wave was caused by what meteorologists described as a dome of high pressure over the Northwest and worsened by human-caused climate change, which is making such extreme weather events more likely and more intense.

Zeke Hausfather, a scientist at the climate-data non-profit Berkeley Earth, said that the Pacific Northwest has warmed by about 3 degrees F (1.7 degrees C) in the past half-century.

That means a heat wave now is about 3 degrees warmer than it would have been before – and the difference between 111 degrees and 114 is significant, especially for vulnerable populations, he noted.

“In a world without climate change, this still would have been a really extreme heat wave,” Hausfather said. “This is worse than the same event would have been 50 years ago, and notably so.”

The blistering heat exposed a region with infrastructure not designed for it, hinting at the greater costs of climate change to come.

US Sen. Maria Cantwell said that the Northwest heat illustrated an urgent need for the upcoming federal infrastructure package to promote clean energy, cut greenhouse gas emissions, and protect people from extreme heat.

“Washington state was not built for triple digit temperatures,” she said.