We often hear about heatwaves and triple-digit temperatures, but there’s a silent threat that makes scorching days even more dangerous—humidity. It’s not just about how hot it is outside; it’s about how your body handles the heat. And when the air is thick with moisture, your internal cooling system struggles to keep up.
Sweating is your body’s natural air conditioning. But when humidity is high, sweat doesn’t evaporate as easily, which means your body can’t release heat efficiently. According to Dr. Vishnu Laalitha Surapaneni, a professor of medicine at the University of Minnesota, this can cause your internal temperature to climb to unsafe levels—sometimes fatally so.
Scientists track this risk using the wet-bulb temperature, a measure that combines heat and humidity. A reading of 95°F wet-bulb temperature for just six hours can overwhelm even healthy individuals. New research suggests that the danger zone might begin even lower, depending on factors such as age, health, and acclimation.
So, how do you know when it’s too hot to be outside safely? Experts recommend monitoring the heat index, which is the “feels-like” temperature that takes humidity into account. A heat index over 103°F is considered dangerous by the National Weather Service.
In sticky, oppressive heat, follow these steps:
- Stay indoors in air-conditioned spaces
- Hydrate frequently
- Limit outdoor activity
- Take cool showers
- Be extra cautious if you have underlying health conditions
And remember: just because you’ve lived in a hot, humid region doesn’t mean you’re immune. Climate change is pushing extremes into once temperate places. Wherever you live, pay attention to how heat and humidity team up—it’s your body’s cue to cool down fast.
