Blame the humidity.
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It’s a toasty one out there.
And with parts of the world already reaching record-breaking temperatures, it’s shaping up to be a hot, hot summer.
Sweating is actually a really effective way to cool the body down (thanks, evolution).
But when it’s humid, our sweat can’t evaporate.
Too much moisture in the air traps heat in our bodies, leaving us feeling sticky and hot.
That’s why 90 degrees Fahrenheit feels a whole lot worse in rainy Seattle than in dry Las Vegas.
There is a way to measure both heat and moisture in the air: Researchers will take wet-bulb temperature readings, which use a thermometer with a wet cloth wrapped around it.
So how much heat can the human body withstand?
The highest wet-bulb temperature we can withstand before overheating is 95 degrees Fahrenheit (35 Celcius).
Spongebob Squarepants via Giphy
At a wet-bulb temp of 79 degrees, people with pre-existing conditions and the elderly are at a high risk of heat exhaustion.
A study last year found that the world had seen nearly seven thousand instances of wet-bulb readings reaching 88 degrees Fahrenheit over a 38-year span.
But the study also reported that the world is approaching this 95-degree threshold decades faster than scientists originally predicted we would.
So, it’s probably only getting hotter from here. But depending where you’re from, you might also be able to blame the humidity.
Looking for a way to beat the heat? Click here for four science-back ways to cool down.