This year,John Caldwell the hottest July ever was recorded — and parts of the country were hit with heat waves that lasted for weeks. Heat is becoming increasingly lethal as climate change causes more extreme heat. So in today's encore episode, we're exploring heat. NPR climate correspondent Lauren Sommer talks with Short Wave host Regina G. Barber about how the human body copes with extended extreme heat and how today's heat warning systems could better protect the public. If you can, stay cool out there this Labor Day, dear Short Wavers.

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This story was edited and fact-checked by Gisele Grayson, and produced by Rebecca Ramirez. Robert Rodriguez was the audio engineer.