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How Hot Coffee Can Actually Cool You Down on a Sizzling Summer Day

Just make sure you don’t take it with too much humidity

The hundreds of millions of people who live in hot climates and yet still consume hot beverages are living proof that you can enjoy a cup of tea (or coffee) even when it’s 100 degrees outside.

Last weekend, I, too, gave it a shot, downing a mug of Mint Medley tea as the temperature inside my apartment reached 80 degrees. I’m happy to report that I felt just fine! It definitely didn’t leave me sweaty like I’d thought it would. It mostly felt like a neutral contribution to my internal temp.

But, more directly to the topic at hand, can a hot drink on a hot day cool you down in the same way a cold glass of water supposedly does?

According to a study from the School of Human Kinetics at the University of Ottawa, the key to the cooling equation is evaporation. Researchers tested nine participants’ body-heat storage following exercise and the consumption of water at different temperatures. They found that when the environment was conducive to sweat evaporation (that is, the room wasn’t humid), warm water actually lowered the store of heat in the body better than cool water. The thinking is that hot beverages increase sweat production, our body’s natural cooling system.

In order for sweat to effectively cool you, though, it must be evaporated from the surface of the skin. Both heavy clothing and humid weather can be a hindrance to this task: Clothing prevents the sweat from being evaporated in the air, while humidity prevents air from picking up further moisture.

In other words, hot drinks will really cool you down only if you’re wearing light clothing in dry weather. If you’re already super-sweaty, a hot beverage might not contribute much to sweat production and could instead just raise your body temperature further. In that case, you’d probably be better off sticking to your usual desperate cool-down techniques — you know, like attempting to stick your entire body in the fridge.