El Nino Retains Strength: IOD-MJO Offer Least Assistance

Key Takeaways:

• El Nino is strengthening rapidly and is expected to evolve into a very strong event during the September-November 2026 period.
• Exceptional Pacific Ocean warming and record-high subsurface heat underline the unusual magnitude of the ongoing event.
• A positive IOD may develop alongside El Nino, although uncertainty remains over its timing and eventual strength.
• Weak MJO conditions and unfavourable ocean parameters are unlikely to support any significant revival of Indian monsoon activity in the immediate term.
• Forecast Validity: Until Next El Nino Update.

Past El Nino events have shown that the strength of El Nino does not necessarily determine the strength of its impact. Yes, strong El Nino events ensure continuation of the event with the least chance of collapsing in between. But such a high magnitude of El Nino, early in the season, is nearly unprecedented, and therefore, comparing it with other data sets of broadly similar events will be like venturing into alien territory. As per the Bureau of Meteorology, the steep ocean surface Pacific warming is supported by excess heat in the subsurface, with equatorial upper ocean heat anomalies during July-Aug 2026 being the highest on record since 1979.

El Nino has often been linked with a weaker monsoon, but experts warn that this year has the potential to be unpredictable for its adverse impact over different parts of the globe. The recent update indicates that El Nino will continue to steadily intensify into a very strong event during Sep-Nov 2026. Multi-model ensemble forecasts from leading global producing centers indicate seasonal average sea surface temperature anomalies may reach an all-time high and could breach the 4°C mark. In addition to a strengthening El Nino, a positive Indian Ocean Dipole is going to overlap the event. Together, these oceanic drivers can amplify regional climate impacts, including droughts, floods and other extreme weather events. However, this statement comes with a rider because there remains some uncertainty about the timing and strength of the IOD.

ENSO: It is a little early to speculate on the El Nino stress on the climate pattern over the next six months or so. Also, it is difficult to assess how its forces will decisively converge with other weather conditions to affect the precise weather forecasts. The location of El Nino warming is critical to the strength of the monsoon – if it is further east in the Pacific, it could have less effect on India's monsoon. But, as the Pacific warming shapes up towards the final leg of the Indian monsoon, more or less, it is identical to the 'canonical' El Nino, which invariably spells doom for the subcontinent monsoon. Failures have outnumbered the benign outcomes in the past few decades.

The equatorial sea surface temperatures are above average across the central and eastern Pacific for the last many weeks. El Nino is strengthening, and its peak is likely to be reached during the fall of the year. There were no major changes in the Nino indices over the last week. Nino 3.4, the marker index for El Nino, remained unchanged, and the temperature anomaly was 1.8°C on 17th Aug 2026. As per BoM, the weekly value of the Relative Nino 3.4 Index for the week ending 16th Aug 2026 was +2.3°C, with the likely trend of growing further.

IOD: The Indian Ocean Dipole is currently neutral. The temperature anomaly has been declining steadily over the last three weeks. The index value for the week ending 16Aug2026 was +0.18°C, the lowest since 19th July 2026.

Models suggest a positive IOD will develop, albeit with uncertainty about its timing and strength. It is unlikely to cross the 1°C mark until mid-Sep 2026.

MJO: The Madden-Julian Oscillation is expected to propagate eastward over the Western Hemisphere during late August and then shift back to the Western Indian Ocean by early September. However, the amplitude of the MJO pulse will remain very weak. Currently, the MJO is being masked by strong El Nino conditions and remains a major factor for anomalous rainfall throughout the global tropics, including the equatorial Indian Seas. It is unlikely to provide any support for the development of a monsoon system over the Bay of Bengal.

None of the ocean parameters are favouring the accentuation of monsoon activity over the Indian subcontinent. The monsoon is getting driven purely by its intrinsic energy. Rainfall distribution remains aberrant, with eastern parts being favoured and the rest of the region nearly starving. There is no immediate reversal expected in this pattern.