Monsoon Has Arrived, So Why Is It Still So Hot? The Science Behind India's New Heat Threat
Rainfall lowers the air temperature, but it also increases the amount of moisture in the atmosphere. This high humidity makes it harder for sweat to evaporate from the skin, weakening the body's natural cooling mechanism. As a result, people continue to feel uncomfortably hot even when temperatures drop after rainfall. According to a September policy brief by the Centre for Science and Environment (CSE), Delhi's heat index frequently crossed 46-50°C during July and August between 2021 and 2025, despite lower actual temperatures. The humid conditions also kept electricity demand high as air conditioners ran for longer hours. The CSE recommends stronger heat action plans with passive cooling measures such as better insulation, shading, natural ventilation and reflective surfaces, along with cooling shelters for vulnerable communities. Experts also suggest increasing green spaces while ensuring adequate airflow, expanding reliable electricity access and improving hospital preparedness for both daytime and nighttime heat. Some cities have already begun adapting. Thane has updated its heat action plan to account for humidity and warm nights, while Bhubaneswar is developing a digital climate-risk dashboard to map heat stress at the building level. As climate change reshapes weather patterns, experts say tracking humidity and the heat
