Everyone knows that as the temperature rises toward a hundred degrees, it begins to get uncomfortably hot.
You might wonder, however, why this is; after all, our normal body temperature is about 98.6 degrees.
If our temperature is in the nineties why do similar air temperatures feel too hot instead of just right?
Well, although you might be 98.6 on the inside, your average skin temperature is nearly 12 degrees cooler. This is because in order to maintain a steady temperature, your body needs to shed heat through your skin. As blood vessels near the skin circulate heated blood from the body's core, that heat disperses, keeping your body cool.
Once the air temperature has risen into the nineties, it has already become hotter than your skin. This means that your skin will now absorb heat from the air, rather than dissipate it. At this point your body is forced to rely on its second method of heat transfer, sweating, to keep from overheating.
That's why temperatures outside need to be lower than your internal temperature to feel comfortable.