Enlarge / The sun sets during a heatwave in Peoria, Arizona, July 11, 2023. (credit: Ash Ponders/Bloomberg via Getty Images)

Just weeks after a third of the US population was hit with air-quality alerts thanks to smoke from climate-change-fueled fires in Canada, 100 million Americans are now under heat alerts. A cap of extra-hot air, known as a heat dome, has settled over the West and South, pushing temperatures relentlessly higher.

The map below shows excessive heat warnings in purple and heat advisories in orange, and the forecast is that things will get worse through the weekend. Highs will stay above 110° Fahrenheit in Phoenix; California’s Death Valley is flirting with 130°; and Texas’ grid is struggling to keep the AC on.

(credit: NWS)

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