Second heat wave of 2022 hits Northwest. A third is in the forecast

For the 11th time this year, Seattle-Tacoma International Airport hit 90 degrees on Wednesday, as did much of south King County and the south Puget Sound region.

The Cascade foothills got even hotter.

Maple Falls, on the Mount Baker Highway, hit 94 degrees, while Marblemount, at the base of the North Cascades, hit 95 degrees.

Much of the Pacific Northwest was put under a heat advisory or heat warning for Wednesday through Thursday night.

The National Weather Service has issued an extreme heat warning for most of eastern Washington through Friday night.

Much of eastern Washington hit triple digits Wednesday, with Richland Airport reaching 107 degrees.

In western Washington, the weather service expects the extreme heat to last just a couple days before cooling off for Friday and the weekend.

With this heat wave expected to be less extreme near the cool waters of Puget Sound, Seattle officials said they are not activating emergency resources yet. But air-conditioned libraries in the city will be open regular hours as safe spaces to cool off.

Heat waves are coming more frequently and more intensely with the earth’s changing climate, especially at night, making it difficult for the many Northwesterners who lack air conditioning to cool off after hot days.

Washington state climatologist Nick Bond said as the climate continues to heat up – due to the heat-trapping gases humans continue to pump into the atmosphere – we can also expect to see extreme temperatures later in the year.

“That window in which we see temperatures that have impacts on humans and our ecosystems is liable to lengthen, especially later in the summer,” Bond said.

After a cooler weekend, another heat wave is expected to hit the Northwest Wednesday through Friday of next week, Bond said, with temperatures in Seattle approaching 90 degrees.

“So right now it looks more likely to be a moderate versus extreme event,” he said.

The Northwest’s previous heat wave, in late July and early August, killed at least 20 people in Washington and Oregon, according to preliminary coroner’s reports.

The region's record-smashing 2021 heat wave killed an estimated 1,200 people in British Columbia, Oregon, and Washington.

Heat waves kill more Americans each year than any other type of weather disaster.