Extreme heat will be more frequent in the Pacific Northwest. Experts say it's not prepared.

By Rachel Ramirez and Cheri Mossburg

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By late weekend, vast swaths of Washington and Oregon will roast in temperatures 20 to 30 degrees above what's normal for this time of year. The National Weather Service in Spokane warned Friday it will be "one of the most extreme and prolonged heat waves" in Northwest history.

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Extreme heat is one of the most pernicious consequences of human-caused climate change, killing more people each year on average than any other weather-related event. Climate change is also going to make record-breaking heat waves more frequent in the future — something researchers and policy experts say the Pacific Northwest is not prepared for.

Seattle and Portland rank first and third, respectively, among cities with the highest proportion of households without air conditioning, according to a US Census Bureau survey of 25 major metropolitan areas. And, experts say, those least likely to have air conditioning are the people who will endure the worst heat — historically underserved communities of color, the elderly, the houseless and low-income residents living in so-called urban heat islands.

"Unfortunately we're not well-prepared, generally speaking in the Pacific Northwest, for heat," Vivek Shandas, a professor of climate adaptation and urban policy at Portland State University, told CNN. "Our [power] grids are largely taxed during the wintertime for heating purposes, but in the summer, there's a lot less capacity in the grid to be able to actually manage some of the major drains on cooling infrastructure that's needed."

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