New climate tool tracks dangerous “humid heat” risks as summer nears | News

Severe Weather Center 13 is looking at a new tool to prevent heat illnesses as summer approaches.

The Climate Shift Index tool from Climate Central now helps measure something Memphis knows well — humid heat.

It establishes a threshold for how hot *and* humid it has to be outside to pose a risk of heat illness for most people, but particularly for older and younger age groups, athletes, and those with underlying health conditions.

It does this by using something called wet-bulb temperature.

“We don’t put out hard numbers about at this temperature or this wet-bulb temperature, this is when you should call practice off. Or this is when you should, you know, move your practice because it’s going to vary from place to place,” says Dr. Lisa Patel of Stanford University, who also says this may be changing thanks to this new tool.

It says a wet-bulb temperature of 77°F puts most people in danger of heat-related illnesses.

Think of wet-bulb temperature as a sweat test.

Too much humidity, and the sweat on your body cannot evaporate.

This test tells us whether the air will let your body cool itself off.

Shel Winkley is a Meteorologist and Engagement Specialist with Climate Central.

“Especially those compounding, when the humidity is high, both nighttime and daytime, and that heat really gets trapped in our homes, that’s when, you know, it’s the most dangerous, especially for some of these folks that can’t afford to run the air conditioner 24/7,” Winkley says.

One example — last July 29th in Memphis.

The high temperature hit 100°F. Overnight lows remained in the 80s. With incredibly high humidity, it was unbearable.

The tool would have ranked the wet-bulb temperature as nearly 82°F… dangerously hot for outdoor activities.

While conditions this weekend will remain in the safe range, it will be our first taste of summer-like weather. 

Dr. Patel says that can still be impactful.

“In the springtime it gets very dangerous because our bodies aren’t adapted yet, we’re behaviorally not adapted yet, and the temperatures can swing. And especially an older body, or a very young one, or somebody with a chronic medical condition is more vulnerable during those periods of time,” Dr. Patel says.

Summer officially begins on Sunday, June 21.