Heat waves in India are becoming longer, stronger and more frequent. A new study by researchers from the India Meteorological Department (IMD) and the Institute of Climate Studies examined how the El Niño–Southern Oscillation (ENSO) influences extreme temperature events across the country and intensifies heatwave conditions during El Niño years.
The researchers analysed data spanning over 59 years (1961–2020) and found that severe heatwaves were more prominent – longer and hotter – during El Niño years. According to the study, ENSO strongly influences extreme temperatures in India.
During El Niño events, the country experiences significantly higher maximum temperatures, longer-lasting heatwaves and a higher frequency of extremely hot days.
The study identified 17 El Niño years between 1961 and 2020 – 1963, 1965, 1966, 1969, 1972, 1982, 1983, 1987, 1991, 1992, 1997, 1998, 2002, 2010, 2015, 2016 and 2019. Out of these, 11 years recorded heatwave spells lasting more than 15 days.
During April, May and June, the sun’s position over the region increases temperatures across India, especially over central, northwestern and northern parts.
The study noted that warmer air from desert regions, carried by changing wind patterns, further raises temperatures. This leads to the formation of climatological low-pressure heat zones and the resulting rising air motion transfers heat to upper atmospheric levels, sometimes triggering strong convective activity.
In contrast, during December to February, the sun shifts to the Southern Hemisphere, leading to lower temperatures. Western disturbances also bring substantial snowfall and rainfall to hilly regions and adjoining plains.
The core heatwave zone in India includes Punjab, Himachal Pradesh, Uttarakhand, Delhi, Haryana, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, West Bengal, Odisha and Telangana, along with the meteorological subdivisions of Marathwada, Vidarbha, Maharashtra and coastal Andhra Pradesh.
The researchers said understanding ENSO is crucial for improving heatwave prediction, preparedness and climate resilience.
