Delhi's Heat Index Shoots Up: IMD Warns of Intensifying Heatwave Threats

Time of India

20-05-2025

New Delhi: The capital is engulfed in a blistering heatwave that feels like an unrelenting furnace, where the very air seems to shimmer with heat.
Tuesday saw temperatures soar to a sweltering 40.8°C, but the true torment lies in the soaring heat index — a brutal combination of temperature and humidity that leaves the city feeling like a pressure cooker.
The rising heat is more than just a discomfort — it's a warning sign of an intensifying crisis, as the India Meteorological Department alerts the public to the growing severity and persistence of heatwaves this summer.
The city, already grappling with urban heat islands, faces a season that threatens to push its limits, challenging both health and infrastructure.
According to India Meteorological Department (IMD) data, the capital recorded a hot and humid day, with a maximum temperature touching 40.8 degrees Celsius (°C), as a combination of clear skies and increased moisture led to uncomfortable weather conditions.
The oppressive weather comes as the India Meteorological Department issues fresh warnings on the severity and persistence of heatwaves expected this summer.
Speaking at ETHealthworld's webinar on "Unpacking Delhi's Deadly Heatwave and Public Health Emergency," Dr M. Mohapatra, Director General of Meteorology at IMD, underscored the unusual patterns and growing intensity of heatwaves across the country. 'This year, we predicted that there will be a higher than normal number of heatwave days,' he said.
'Usually, there are about 7 to 10 days of heatwaves in different parts of India each year, but this year, we expect an increase of about 6 to 10 additional days.'
While the frequency may be slightly less compared to last year, Dr. Mohapatra emphasized that heat will still be intense and widespread. So far, March and April have seen severe heatwave conditions in western India, especially Gujarat and Rajasthan, along with parts of Haryana, Delhi, Punjab, and Jammu.
Eastern states like Bihar, Jharkhand, West Bengal, Odisha, and Uttar Pradesh have also reported isolated heatwave episodes. Central India, particularly Vidarbha and southern Madhya Pradesh, may experience more such events in late May.
'The heatwave is one of the severe weather hazards, which affects not only human lives and property, but also has wide and adverse impacts on various sectors of society,' he said, highlighting risks to agriculture, power supply, water availability, and public health.
Dr. Mohapatra also pointed out that rising urbanization is intensifying the urban heat island effect, where central parts of cities like Delhi witness higher temperatures due to concrete structures, dense populations, and less green cover. 'All these are contributing to increased vulnerability of individuals and urban systems,' he said.
In response, IMD has enhanced its early warning services, especially for urban centers like Delhi. The department now issues district-specific forecasts for the city's seven districts instead of a general forecast, allowing for better preparedness and targeted advisories.
Importantly, the IMD has begun incorporating relative humidity and temperature-humidity indices in its forecasts to better assess real-world discomfort and risk levels. With every 1°C rise in temperature, atmospheric humidity can increase by around 7 per cent, worsening conditions for the population.
Another concern flagged by Dr. Mohapatra is the combination of heatwaves with high night-time temperatures—known as warm nights—which prevent the human body from recovering from daytime heat exposure and significantly increase health risks, especially for the elderly and those with comorbidities.
To offer a more comprehensive picture, IMD also overlays air quality data (PM2.5 and PM10 levels) with heatwave alerts in cities like Delhi. 'This enables a composite assessment by the public and relevant agencies to take timely action,' said Dr. Mohapatra.
He added that persistence is key: a heatwave lasting just a couple of days might not be disastrous, but if it continues for four or five days, especially in densely populated or vulnerable areas, it can lead to high mortality and morbidity.
As India heads into the peak of summer, weather experts are urging citizens and authorities alike to take precautionary steps. With climate change, urban expansion, and increasing atmospheric moisture intensifying the impact of heatwaves, this summer may be yet another reminder of how urgent climate resilience measures have become