I knew why if feels colder in the wind (wind chill) but I didn’t know why it feels hotter in the humidity. Now I know.

Some basic facts to start. Relative humidity is the % of water in the air. Hotter air can hold more water. So 100% humidity would mean the air is saturated with water.

So… the reason it feels hotter?

Our bodies rely on evaporation to stay cool. Ever hear of a little thing called sweating? At higher relative humidities, it’s harder to evaporate that sweat, so you don’t cool off as much, so it seems like it’s hotter. Eureka. Read more about it at the source.

Source: American Institute of Physics