A New Way to Measure Heat Risks for People

For all the images of ski resorts and snow-capped peaks, Colorado is experiencing shorter winters and hotter summers that are increasingly putting people at risk for heat-related illnesses. Yet until this year, the National Weather Service hadn’t issued a heat advisory for the Denver metropolitan area in 13 years.

That’s because the heat index commonly used by the weather service to gauge the health risks of hot weather relies on temperature and humidity. Colorado’s climate is so dry that reaching the thresholds for that kind of heat advisory is nearly impossible.

But...