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Heat plus humidity
High humidity slows sweat evaporation, so your body cannot cool as efficiently. The heat index combines temperature and relative humidity into a single “feels like” value that correlates better with heat illness risk than temperature alone.
Interpretation
When the heat index climbs, take extra breaks, drink water, and seek shade or air conditioning. This implementation follows a standard regression used for hot conditions; it is an estimate for awareness, not a medical instrument.