The India Meteorological Department is preparing to revise the existing IMD heatwave rules in the country, as officials believe the current criteria are not fully suitable for India’s varied geographical conditions. According to sources, the updated parameters will help states like Kerala issue more accurate and timely heatwave warnings during periods of extreme weather.
Officials from the India Meteorological Department said Kerala faced severe heat and humidity this summer, making it difficult to issue official heatwave warnings under the present IMD heatwave rules.
Rare Anti-Cyclone System Increased Heat in Kerala
According to officials, Kerala experienced unusual weather conditions this year due to the formation of an anti-cyclone system near the Karnataka–Maharashtra coast. Such systems are generally seen over north-western India, but this time it formed closer to the southern region.
A senior IMD official explained that the anti-cyclone caused downward movement of air, pushing warm air towards the surface and preventing temperatures from cooling during the night. Because of this, several areas in Kerala recorded night temperatures 3 to 4 degrees Celsius above normal.
The situation highlighted the limitations of the current IMD heatwave rules, especially in coastal states where humidity and heat stress can become dangerous even without extremely high daytime temperatures.
Why IMD Heatwave Rules Need Changes
At present, the India Meteorological Department declares a heatwave in coastal regions only when temperatures touch 37 degrees Celsius or more along with a departure of 4.5 degrees Celsius above normal.
For plains, the threshold is 40 degrees Celsius, while hilly areas require temperatures of 30 degrees Celsius with similar departures from average conditions.
Officials said the current IMD heatwave rules also require these conditions to be recorded at two weather stations within a state before issuing a heatwave warning.
However, Kerala rarely records such conditions simultaneously in two locations, despite severe heat stress and rising cases of heatstroke being reported across the state.
Kerala Witnessed Severe Heat Stress This Summer
Even though official heatwave declarations were limited, Kerala experienced prolonged periods of extreme heat and humidity this summer. Authorities reported several heatstroke cases despite regular advisories issued by the India Meteorological Department and the state disaster management authority.
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Officials believe revising the IMD heatwave rules will allow quicker warnings and better public safety measures in states facing climate-related temperature changes.
IMD Predicts Below-Normal Monsoon
Experts have also warned that Kerala is becoming increasingly vulnerable to climate change due to rising temperatures and erratic monsoon patterns.
Meanwhile, the India Meteorological Department has predicted a below-normal monsoon this year, noting that the country is witnessing two consecutive El Niño years for the first time in recent history.
The proposed changes to the IMD heatwave rules are expected to improve India’s weather warning system and help authorities respond more effectively to extreme heat conditions in the future.