By the time you are reading this, we’ve likely hit our first official 100-degree day of 2025. Surprisingly, despite what’s been a relatively mild summer, our firefighters and paramedics have already responded to more heat-related medical emergencies than expected.

One possible reason? A false sense of safety. These days, many people rely on smartphones, smartwatches, or voice assistants like Siri to check the weather—only to hear that the outside temperature is in the low to mid 90s, which may seem bearable. But what’s often overlooked is humidity, and that’s when the heat index becomes a hidden and potentially dangerous factor.

What Is the Heat Index?

The heat index measures how hot it feels when relative humidity is added to the actual air temperature. When humidity is high, sweat doe

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