By Surabhi Gupta
New Delhi: Heatwave conditions typically manifest between March and June, but dramatic fluctuations in climate patterns have emerged in 2025. Heatwaves have not only struck much earlier this year but have also been simultaneously accompanied by an increase in warm nights, showcasing the vagaries of climate change in terms of warming nights and daytime temperatures, as forecast by the India Meteorological Department (IMD) regarding the implications of temperature spikes throughout the country.
Record-Breaking Early Heatwave
The increase in temperatures was first noted on February 26, when Mumbai recorded 38.7 degrees Celsius, nearly six degrees Celsius above normal. Although the IMD warned of heatwave conditions, the states did not formally declare a heatwave at that time. However, due to the increasingly high temperatures, the littoral states declared heatwave conditions as the daily temperatures were hovering over 37 degrees Celsius (per the IMD).
The highest temperature in this season was recorded on March 16 in the Boudh district of Odisha at 43.6 degrees Celsius, the day after the previous high of 41.7 degrees Celsius on March 15. In addition, other states witnessed record-high temperatures including temperatures at 42 degrees Celsius in Jharsuguda and at 41.7 degrees Celsius in Bolangir. This made Odisha the home to the three hottest locations in the country, stating that it was one of the most intense heatwaves recorded in recent times.
Dr Shashi Kant, an IMD scientist said, "Heatwave conditions likely to abate from East India except from interior Odisha from mid march."
Expert Warnings on Climate Change
Environmentalist Manu Singh termed the early heatwaves coupled with rising nighttime temperatures as a direct and alarming indicator of anthropogenic climate change. "Notably, India recorded its first-ever winter heatwave on February 25, affecting Goa and Maharashtra, a phenomenon previously unheard of in India's historical climate records," he said.
Emphasising the importance of rising nighttime temperatures he said, "Increased minimum nighttime temperatures impose oxidative physiological stress on humans, making the recovery from daytime heat exposure difficult. Vulnerable populations, including the elderly, children and low-income communities without access to cooling, are disproportionately affected. Studies, including the Lancet Countdown (2023), have confirmed that higher nighttime temperatures exacerbate health risks, worsening overall heat stress."
Record Heat and Rising Warm Nights
IMD mentioned in a media report that February 2025 was not only the warmest but one of the driest months in the past 125 years. The warming trend has also continued into March and nighttime temperatures have still been well above normal. Scientists say the number of very warm nights (warm minimum temperatures) has been increasing at alarming rates for the last decade due to climate change impacts. Last year, a global study found that very warm nights in India have risen critically over the past decade due to the intensifying climate change.
"February 2025 was the hottest since 1901, with the average mean temperature for the month settling at 22.04°C. With 29.07°C, (last) February recorded the second highest maximum temperature since 1901, with (an) anomaly of 1.49°C". Last February also had the all-time high minimum temperature at 15.02°C, above normal by 1.20°C," the IMD data states.
The 'AR6 Synthesis Report: Climate Change', released during the Intergovernmental Panel On Climate Change's (IPCC) 58th session held in Interlaken, Switzerland from March 13 to 19, indicates that Central India sustained the greatest impact from the anomalous heatwave when averaged over the month, as the maximum temperature was 1.94 °C higher than normal, while the average temperature was 1.73 °C higher than normal.
Impacts on Health and Agriculture
Prolonged exposures to extreme daytime and nighttime temperatures pose extreme health threats. Singh has also indicated that increased nighttime temperature can alter the normal sleeping cycle, which can lead to increased mortality, particularly amongst the vulnerable population. Agricultural output is under threat as well. A report from the National Center for Biotechnology showed that a 1°C increase in nighttime temperature can decrease wheat yield by 6 per cent and rice yield by 10 per cent. Warmer nights can also influence grain quality, chalking rice, making it unpalatable and potentially altering the conditions of grain nutrition.
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