On This Day in 2021: The Pacific Northwest Heat Dome

On this day in 2021, Portland International Airport hit 116 degrees. It had already broken its all time record twice that week, reaching 108 on the 26th and 112 on the 27th. Seattle, Salem and much of British Columbia set records of their own, several by margins of nine degrees or more. A ridge of high pressure had parked over the region and trapped heat underneath it, a pattern now widely called a heat dome.

The Pacific Northwest was the wrong place for it. Summers there are mild, so air conditioning was uncommon in homes and apartments, and buildings were designed to hold warmth rather than shed it. Hundreds of deaths across the region were attributed to the heat, most of them indoors and most of them people who lived alone. Roads buckled, power cables sagged, and cooling centers filled.

Heat kills quietly and it kills inside, which makes it the hazard most likely to be underestimated by people who have never needed to plan for it. A house that stays livable through a stretch like that is mostly a matter of shade, airflow, hydration and one room you can actually keep cool, which is the core of extreme heat preparation for any home. Getting fluids right matters more than most people expect, and survival hydration covers what the body is actually losing.