Tue Apr 22 14:59:50 UTC 2025: ## MP Urges India to Revise Heatwave Definition to Account for Humidity and Nighttime Temperatures
**Chennai, April 22, 2025** – Member of Parliament Kanimozhi Karunanidhi has called on the Indian government to update its definition of heatwaves to better reflect the escalating climate crisis. In a letter to the Minister of State for Earth Sciences, Jitendra Singh, Ms. Karunanidhi advocated for the inclusion of humidity levels and rising nighttime temperatures in the India Meteorological Department’s (IMD) criteria.
This appeal follows record-breaking temperatures in 2024, including October being the hottest in 123 years with a temperature anomaly of +1.23°C. The year also saw the highest annual minimum temperature anomaly since 1901 (+0.90°C), highlighting dangerously warm nights impacting public health. The current IMD guidelines, reliant primarily on air temperature, fail to capture the exacerbated effect of high humidity.
Ms. Karunanidhi emphasized the need for composite indices like the Wet Bulb Globe Temperature or Heat Index, which consider both temperature and humidity for a more accurate assessment of thermal stress. She pointed out that in humid coastal areas, even moderate temperatures can feel significantly hotter and pose serious health risks. She cited World Health Organisation recommendations that nighttime temperatures above 24°C can negatively impact cognitive function and increase heat-related illnesses.
The MP’s recommendations include not only revising heatwave definitions but also implementing region-specific criteria, particularly for coastal zones, and launching public awareness campaigns to educate citizens about heat and humidity risks and preventative measures.
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