Nino 3.4 Remains Steady: Nino 1+2 Shoots High

Key Takeaways:

• El Niño has more than a 90% probability of becoming a very strong event during the Northern Hemispheric fall and winter of 2026-27.
• Exceptionally high Pacific Ocean and sub-surface temperature anomalies point towards an unusually powerful ENSO event.
• The IOD remains neutral despite El Niño strengthening, reducing its chances of offsetting El Niño's adverse influence on the Indian monsoon.
• The southwest monsoon could end with a significant seasonal rainfall deficit and drought-like conditions across several pockets of India.
• Forecast Validity: Until Next Update.

El Niño is strengthening, with a more than 90% chance of a very strong event during the Northern Hemispheric fall and winter of 2026-27. This year, the El Niño weather pattern has the potential to be the strongest ever. Ocean temperatures are likely to be hotter than ever since measurements began. Notwithstanding its final outcome, climate scientists have sounded an alarm for all those affected to prepare for the worst.

The ensemble forecasts from leading global centres indicate that seasonal average sea surface temperature anomalies may reach or exceed 3°C shortly. Sub-surface temperatures have become extraordinarily warm, with anomalies in the range of +6°C to +8°C. The growing impact of a powerful El Niño can be partially offset by a strong positive IOD, but the odds do not seem to be in favour. The IOD is just not picking up and has remained neutral for the last five weeks.

The southwest monsoon is now in its last leg, and under the weight of the growing El Niño, the IOD is unlikely to rescue the crippling Indian monsoon. In any case, the remaining period of the monsoon will have to rough out the ill effects of El Niño without any external support for mitigation.

ENSO: A very strong signal in the Niño 3.4 region does not necessarily mean a crushing impact on global weather. Undoubtedly, such a powerful El Niño is a grey swan event that has the potential to churn out chaotic climatic patterns carrying massive hazardous consequences. But then, ENSO is only one of the many factors that can influence intra-seasonal and inter-seasonal variations. However, such exclusive and outlier events do overshadow the role of other sister concerns of meteorology, which otherwise have the capacity to partially balance out the adverse impact.

Different standards and norms are followed by the Bureau of Meteorology (BoM) and the Climate Prediction Center (CPC) for El Niño. The threshold value itself varies from a temperature anomaly of 0.5°C for CPC to 0.8°C for BoM.

As per BoM, the Niño 3.4 index is steadily rising, and the latest value, as of 06 September 2026, was +2.54°C. The CPC Niño 3.4 index has remained nearly constant, with an anomaly of 1.8°C for the last five weeks. However, the El Niño advisory is ‘ON’, and the forecast of a very strong El Niño event remains unchanged, with probability in excess of 90%.

Niño 3 and Niño 1+2 continue to rise incrementally. The Niño 1+2 anomaly has surpassed the earlier highest record of 3.5°C during the 2023-24 event on 24 July 2023. It may increase further to set a new record in the coming weeks.

IOD: The Indian Ocean Dipole is currently neutral. The latest IOD index value for the week ending 06 September 2026 was +0.25°C. After remaining above the positive threshold for three weeks, the index has eased back into the neutral range over the past four weeks.

In the neutral phase, sea surface temperatures remain relatively balanced, with wind and ocean circulation operating close to their traditional averages. Historically, the IOD index turns positive during El Niño conditions. This time, it is an exception that even with a super El Niño forecast, the index has defied expectations and loitered mostly within the neutral range.

Models continue to suggest that a positive IOD could develop during the autumn season, although the forecast magnitude of the event has decreased in recent model runs.

MJO: The Madden-Julian Oscillation has been active alright, but has not been propagating eastward efficiently. It seems to be lingering in Phases 6 and 7 over the Western Pacific. It is finding it difficult to resolve the intra-seasonal signal within the much stronger and stationary ENSO signal.

It may continue to meander over the Western Pacific for the remainder of September and move to the Western Hemisphere and Africa during the first week of October. MJO is unlikely to offer any constructive support for the development of an active monsoon system over the Indian Seas.

The southwest monsoon continues to have a large seasonal rainfall deficit, and the shortfall is alarming over the South Peninsula and western parts. While the central and eastern parts may get a decent spell of consolatory showers, the misery remains with the southern and northern parts.

The season is heading to end with drought-like conditions over many pockets of the country.