Why humidity makes heat feel unbearable: The science explained

Relative humidity measures the amount of moisture present in air compared to the maximum amount it can hold at a given temperature. During India's sweltering summers, this metric becomes critical to understanding why some days feel more intolerable than others, even when temperatures remain similar.

The human body relies primarily on sweating to regulate its internal temperature during hot weather. As perspiration evaporates from the skin, it dissipates heat and cools the body. However, when relative humidity rises, the air becomes saturated with moisture, significantly slowing down this evaporation process. In high-humidity conditions, sweat accumulates on the skin rather than evaporating, drastically reducing the body's cooling efficiency.

This explains why coastal regions and areas near water bodies often experience more oppressive heat than inland regions at comparable temperatures. A day with 35 degrees Celsius and 30 percent humidity feels considerably more bearable than the same temperature at 70 percent humidity, as the body can shed heat more effectively in drier conditions.

Meteorologists and health experts emphasize that high humidity combined with elevated temperatures poses serious health risks, including heat exhaustion and heat stroke. Vulnerable populations—elderly individuals, children, and those with chronic conditions—face heightened risks. During such conditions, increased water intake, staying indoors during peak heat hours, and seeking air-conditioned spaces become essential precautions for maintaining health and safety.