IMD to revise heatwave declaration parameters as Kerala faces warnings challenges

The IMD has predicted a below-normal monsoon this year, noting that two consecutive El Niño years are being witnessed.

Throughout Kerala, temperatures this summer were 3–4°C higher than usual, and the state reported multiple cases of heatstroke despite regular warnings issued by the IMD and the state disaster management authority.

The current heatwave declaration parameters require a 37°C maximum in coastal areas with a 4.5°C departure, 40°C for plains with a 4.5°C departure, and 30°C for hilly regions with a 4.5°C departure, and also require these conditions to be recorded at two stations in the state.

For the first time, weather forecasts were made based on an anti-cyclone system that formed near the Karnataka–Maharashtra coast. This anti-cyclone caused downward air movement, pushing warm air to the surface and preventing it from dispersing at night, leading to unusually hot nights in Kerala.

Kerala has faced difficulties issuing heatwave warnings because of the limitations of the existing parameters. The state experienced severe heat and humidity this summer, with night temperatures 3 to 4°C above normal and forecasts influenced by an anti-cyclone system near the Karnataka–Maharashtra coast.

The IMD, along with its technical partners, will soon revise the criteria for declaring heatwave conditions in the country, as the present parameters do not suit India's geographical conditions, according to official sources here. Changes will be implemented shortly and will include a consultation with the Disaster Management Authority before finalising parameters.