Climate Change Crisis in India: IMD Plans Major Overhaul of Heatwave Warning Rules

India’s weather authorities are preparing to overhaul the country’s heatwave declaration system as rising temperatures and changing climate patterns expose the limitations of the existing framework, particularly in southern states like Kerala .

The India Meteorological Department (IMD) , along with its technical partners, is expected to soon revise the parameters used to officially declare heatwave conditions. Officials say the current rules were framed decades ago and no longer reflect the rapidly changing climatic realities across the country.

The move comes after Kerala witnessed one of its most intense summers in recent years, marked not just by scorching daytime temperatures but also by unusually warm and humid nights. Weather experts say the state experienced a rare anti-cyclonic system near the Karnataka–Maharashtra coast, something typically seen over northwestern India.

According to IMD officials, this unusual atmospheric system trapped warm air close to the surface, preventing temperatures from cooling during the night. As a result, several parts of Kerala recorded night temperatures three to four degrees Celsius above normal , worsening heat stress across the state.

Despite the severe conditions, the IMD could not officially declare a heatwave in many places because the present criteria are heavily dependent on fixed temperature thresholds and readings from at least two weather stations in a state. Officials admit that these parameters often fail to capture the intensity of heat stress experienced in coastal and humid regions like Kerala .

Currently, a heatwave in coastal areas is declared only when temperatures touch 37 degrees Celsius with a significant departure from normal levels. In plains, the threshold is 40 degrees Celsius , while hilly regions require temperatures above 30 degrees Celsius along with a substantial deviation from average conditions.

Experts argue that such benchmarks do not adequately reflect the dangers posed by humidity and prolonged warm nights, both of which significantly increase the risk of heatstroke and dehydration.

Kerala reported several heatstroke cases this summer despite repeated advisories from weather and disaster management authorities. Climate experts now warn that the state is steadily emerging as a climate change hotspot , with rising atmospheric temperatures, erratic rainfall patterns, and increasingly unpredictable monsoons.

The concern has grown further after forecasts indicated the possibility of a below-normal monsoon , amid back-to-back El Niño influenced years, an uncommon phenomenon that could intensify weather extremes across the region.

Officials said the revised heatwave parameters are being finalised in consultation with disaster management authorities and are expected to allow more region-specific and realistic warnings in the future.