India, May 17 -- India's heat wave warning system is set for its most significant revision in years. The India Meteorological Department (IMD) is planning to expand its criteria for heat alerts to include a percentile-based threshold - a shift that would, for the first time, formally capture the kind of humid, oppressive heat that coastal regions routinely experience but that existing guidelines have long failed to flag.

Under the new framework, a heat alert will be triggered when maximum temperatures exceed the 95th percentile for a given location - the point above which only 5% of all historically recorded temperatures fall.

The change is designed to address a specific gap: areas, particularly along the coast, where temperatures may n...