Pune: Though India Meteorological Department (IMD) has forecast below-normal rainfall for the country during the 2026 southwest monsoon amid evolving strong El Niño conditions, climate scientists say there may still be a possible late-season support system emerging over the Indian Ocean.Scientists are closely tracking the Indian Ocean Dipole (IOD), a major climate pattern in the Indian Ocean that is currently in a neutral phase but is expected to gradually turn positive during the latter half of the rainy season.“A positive IOD can somewhat offset the impact of El Niño, though its influence is likely to be felt more during the latter part of the monsoon season since positive IOD conditions have not developed yet,” said Ankur Srivastava, scientist at Indian Institute of Tropical Meteorology (IITM), Pune.The IOD refers to temperature differences between the western and eastern Indian Ocean. During a positive IOD phase, waters near Indonesia become cooler than normal while the western Indian Ocean turns warmer. This shift changes atmospheric circulation patterns and has historically been linked to improved monsoon rainfall over parts of India.“According to climate model forecasts, a positive IOD signal is expected to strengthen gradually during the second half of the southwest monsoon and peak during the Sept-Nov period, which is when IOD events typically mature,” Srivastava said.The development is significant because strong El Niño events are usually associated with weaker Indian monsoons. Srivastava said, “El Niño and the IOD are closely connected climate systems, with El Niño often helping trigger positive IOD formation by altering equatorial wind patterns and ocean upwelling near Sumatra and Java.”He said, “Some of the strongest recorded positive IOD events occurred alongside or after major El Niño conditions.”Experts, however, cautioned that the projected 2026 positive IOD remains moderate at present and confidence in forecasts is currently higher for the late monsoon and post-monsoon months, rather than the early part of the rainy season.GP Sharma, president of Skymet, said, “At present, the Indian Ocean Dipole (IOD) is neutral and marginally negative. Models are projecting that the IOD could turn neutral to positive later in the rainy season, likely after July.”He said, “A positive IOD is generally considered favourable for monsoon and can help partly offset the impact of El Niño. In fact, during an El Niño year, a positive IOD is one of the few large-scale climate factors that can help rescue the monsoon to some extent, especially during Aug and Sept.”Sharma said, “Unlike the Madden-Julian Oscillation (MJO), which is short-lived and transitory, the IOD is a more stable climate parameter. Once it turns positive, it tends to persist and can support monsoon activity over a longer period.”He said, ”However, forecasts for the second half of the monsoon still needed to be treated with caution at this stage because the projected positive IOD has not yet evolved.”An IMD official said some climate models were indicating possibility of a positive IOD developing during Aug or Sept. “The IMD’s Monsoon Mission Climate Forecast System model is currently showing neutral IOD conditions through the season,” the official said.“Several international meteorological centres are also not strongly indicating a positive IOD at present. There is still uncertainty and we will need to monitor how conditions evolve over the coming weeks,” the official said.
