NASHVILLE, Tenn. (WKRN) — While Middle Tennessee is no stranger to hot summers, this week’s combination of sky-high humidity levels and temperatures nearing 100° is particularly dangerous.

According to Krissy Hurley, the Warning Coordination Meteorologist at the National Weather Service Office in Nashville, heat is the number three weather killer in Middle Tennessee. “Heat across the United States is the number one weather-related killer. Now here in Tennessee, tornadoes, and floods are still neck and neck, but heat is number three. So it’s something that we should not take lightly,” said Hurley.

It’s been hot enough for Nashville’s National Weather Service to issue an Excessive Heat Warning, a rarity for the Nashville metro area. “An Excessive Heat Warning, we haven’t issued one of those in 10 years,” said Hurley. “We definitely don’t take it lightly because that should signify that we mean business about this heat and it is incredibly dangerous.”

Middle Tennessee has had some vigorous heat waves in the past. A decade ago, 2012 brought some very hot weather, Nashville hit 109 on June 29th of that year, the hottest temperature ever for the city. August of 2007 brought 15 days of 100 plus heat. What makes this week’s heat wave different is the humidity.

“The difference between this summer’s heat compared to 2007, where we were really hot, is that was more of a dry heat. Our low temperatures were able to actually dip into the upper 50s and 60s, and the high temperatures were getting well above the 90-degree mark, the 100-degree mark,” said Hurley. “But this summer, we have a lot of humidity. And with that humidity, our temperatures just cannot fall overnight, because there’s too much moisture in the atmosphere.”

Humid heat is more dangerous than dry heat because it prevents your sweat from evaporating and cooling you down. It’s much harder to cool off with these high dewpoints in place. These warm nights make heat-related illnesses more likely, especially for those without air conditioning. 

“People really need to pay attention to their bodies. If you’re feeling dehydrated, if you’re feeling unwell, you need to take action quickly to prevent heatstroke and make things worse,” said Hurley.