Why does humidity make heat worse?

Answer: Sweat can't evaporate efficiently

Humid air is actually hotter — Wrong. Humidity doesn't change air temperature—thermometer reads same. Feels hotter because sweat evaporation (body's cooling) is inhibited.

Water vapor conducts heat better — Wrong. Water vapor isn't better heat conductor. High humidity feels worse because it prevents efficient sweat evaporation cooling.

Sweat can't evaporate efficiently ✓ — Correct! Evaporative cooling blocked! Humidity makes heat feel worse: (1) Body cools through sweat evaporation. (2) Evaporation requires dry air—water molecules escape into air. (3) High humidity—air already saturated with moisture. (4) Sweat can't evaporate—stays on skin. (5) No evaporation = no cooling. Heat index: combines temperature + humidity (how hot it feels). 35°C with 80% humidity feels like 50°C+! Dangerous: heat stroke risk. Dry heat (deserts): sweat evaporates instantly—better cooling despite high temperature!