Forecast consistency across multiple ensemble systems and evolving oceanic conditions suggest there is a very high probability of El Niño developing this summer, according to two renowned weather scientists/researchers. An El Nino typically brings a poor south-west monsoon to India, including droughts, though with exceptions.
businessline spoke to Swadhin Behera, Director, Application Research Laboratory, Japan Agency for Marine-Earth Science and Technology (Jamstec), and visiting professor at The University of Tokyo; and Saji Hameed, Professor, Department of Computer Science and Engineering/Division of Computer Science, University of Aizu, Tokyo.
Saji Hameed
Interaction with a likely emerging positive Indian Ocean Dipole (IOD) that mimics El Nino-La Nina in the Indian Ocean, will decide the extent of El Nino’s impact on India. The SINTEX-F model at Application Research Laboratory and many other models predict a positive IOD this year, in which the western basin of Indian Ocean warms up relative to east, which is found helpful to a prevailing south-west monsoon.
If it evolves during the summer, it will reduce the El Niño impact in central and eastern India, Behera opined. Ensemble mean across several dynamical models suggests a moderate to strong El Niño, he added. However, individual ensemble members within SINTEX-F and other systems indicate the possibility of a stronger event.
Super El Nino
Saji Hameed said: “We have a theory about extremely strong El Nino’s – the so-called super El Nino’s. Actually, they are more than just strong El Nino’s. Our analysis suggests that they occur only when an IOD and an El Nino occur simultaneously. The Jamstec forecast model seems to be the only model in the world that has successfully predicted many IOD occurrences of the past. And, its El Nino forecasts are not bad either.
Hameed adds: “The Jamstec model predicts occurrence of both an El Nino and a positive IOD in 2026. If that prediction turns out to be true, then there is a more than good chance that we will see a super El Nino in 2026/2027, similar in magnitude to the 1997/1998 super El Nino.”
Tenuous linkage
But for India, 1997-98 had turned out to be a normal monsoon year, indicating how the inter-linkages may be tenuous at best. IOD typically develops during spring April–May, intensifies through south-west monsoon (June–August) and reaches peak strength during autumn (September–November), before decaying in December.
Excerpts from interview with Swadhin Behera:
Could you explain the latest SINTEX-F predictions in nickels and dimes?
Latest forecasts from the SINTEX-F seasonal prediction system indicatethe development of an El Niño event during the summer of 2026. In fact, SINTEX-F has consistently predicted El Niño conditions since October last year, demonstrating relatively stable lead-time predictability.
This outlook is broadly consistent with forecasts from other major dynamical prediction systems, particularly those contributing to the North American Multi-Model Ensemble (NMME). The multi-model consensus increases confidence in the projected warming of the central-to-eastern equatorial Pacific. Persistence of subsurface heat content anomalies and their eastward propagation are key precursors currently supporting this forecast.
What is the likelihood of El Niño occurrence?
The so-called spring predictability barrier often limits ENSO forecast skill when predictions cross the spring. In recent years, advances in ocean data assimilation, improved model physics, and better representation of coupled air–sea feedbacks have substantially enhanced performance of dynamical prediction systems.
Importantly, we have experienced persistent La Niña conditions over past two years. Such multi-year La Niña episodes typically lead to a gradual build-up of warm water volume in western Pacific warm pool. This recharge of equatorial heat content is a fundamental component of the ENSO recharge–discharge oscillator framework.
Once the system transitions from the “recharged” state, the accumulated subsurface warm water can propagate eastward and precondition the basin for El Niño development.
In fact, recent observations from TAO/TRITON buoy array show the transmission of downwelling equatorial Kelvin waves from western Pacific toward central and eastern Pacific. These waves deepen the thermocline in the east and transport subsurface heat eastward, providing a dynamical trigger for surface warming.
Given the consistency across multiple ensemble systems and the evolving oceanic conditions, I would say there is a very high probability of El Niño development by boreal summer.
Will it be a strong event?
The ensemble mean across several dynamical models suggests a moderate to strong El Niño. However, individual ensemble members within SINTEX-F and other systems indicate possibility of a stronger event.
At this stage, uncertainty remains regarding the amplitude. Much will depend on:
1. Strength and persistence of westerly wind bursts,
2. Evolution of subsurface heat content,
3. Feedback strength in Bjerknes coupled ocean–atmosphere system. If positive feedbacks intensify during late spring and early summer, the event could strengthen beyond moderate intensity.
Could projected El Niño lead to a better north-east monsoon for South India?
While seasonal rainfall prediction skill remains modest compared to SST forecasts, SINTEX-F currently predicts above-normal rainfall over southern India and Sri Lanka during north-east monsoon season. If this materialises, it may partially compensate for expected south-west monsoon deficits, especially for Tamil Nadu and adjoining regions.
However, the rainfall in both monsoon seasons will depend on several factors.
1. Spatial structure of El Niño, including its peak intensity during June-September.
2. Interaction with the IOD. SINTEX-F and many other models predict a positive IOD this year. If it evolves during the summer, it will reduce the El Niño impact in central and eastern India.
3. Intra-seasonal variability (for instance, MJO wave activity).
Is El Niño becoming harder to detect under global warming?
There is growing evidence that under anthropogenic warming, background tropical Pacific SSTs are rising, which can mask or alter the apparent structure of El Niño anomalies.
Recent El Niño events have shown warm SST anomalies extending across much of the tropical Pacific basin. This broader warming may be influenced by:
1. Long-term global warming trends
2. Decadal variability (as in Pacific Decadal Variability)
3. Changes in mean-state trade wind strength.
In such a warming background, relative SST anomalies (deviations from climatology) may appear spatially broader or less distinct, making classification more nuanced. However, dynamical indices (such as Niño3.4 SST anomalies and subsurface heat content) remain reliable diagnostic tools.
Published on February 23, 2026