Why Humid Heat Feels So Unbearable and Makes You Sweat More
Forbes
Last updated: June 30, 2026
Hot weather feels significantly worse when humidity is high due to the body's primary cooling mechanism: sweat. High humidity hinders the evaporation of sweat, making it difficult for the body to regulate its temperature effectively. This article explains the physiological reasons behind this phenomenon.
- When air is saturated with water vapor, sweat on the skin struggles to evaporate. Evaporation is the process by which heat is released from the body, cooling it down. High humidity means the air already holds a lot of moisture, so it cannot absorb more moisture from sweat. This leads to sweat accumulating on the skin, providing little to no cooling effect. The body then continues to produce more sweat in an attempt to cool down, resulting in excessive sweating and a feeling of being overheated and uncomfortable. This is why humid heat is perceived as more oppressive than dry heat, even at the same temperature. The U.S. and Canada are anticipating a "heat dome," a period of excessively hot weather, making this understanding particularly relevant for public health and personal safety.
