Surge in ‘Danger Days’ Just Around the Corner

Chances are you’ve never heard the phrase “danger day” when it comes to weather.  That’s because they’re rare.  You’ll want to get to know it, though, because climate change is about to make them a lot more common over the next 15 years.

A danger day is when the combination of heat and humidity (also known as the heat index) make it feel like it’s 105°F or hotter.  Warming temperatures are about to push U.S. cities into a new regime where danger days happen regularly.

Of the 144 U.S. cities Climate Central analyzed, only 12 of them averaged more than one danger day per year since 1950.  Most of those cities are clustered in the South where humidity tends to be worst in the morning while temperatures peak in the late afternoon.

But by 2030, a whopping 85 cities — home to nearly third of the U.S. population -- are projected to deal with at least 20 danger days annually.  Only nine cities are projected to experience less than one danger day per year.  By 2050, just three cities could have as little as one danger day per year, while 109 cities that are home to 125 million Americans will experience 20 danger days or greater annually.

Danger days make  going outside oppressive and physical activity a risky proposition. Extreme caution days —  days when the heat index tops 90°F — also pose a hazard for health and are just plain miserable (unless you’ve got a beach or movie theater nearby).  These dangerous heat days pose the greatest threat to kids and the elderly, who are more sensitive to the heat, along with anyone that doesn’t have easy access to air conditioning.

Read more at Surge in ‘Danger Days’ Just Around the Corner