European forecaster projects El Niño to form by May, doesn’t rule out super El Niño
The European Centre for Medium-Range Weather Forecasts (ECMWF), one of the world's most authoritative seasonal forecasters, projects the formation of El Niño conditions by May 2026, with the possibility of a super El Niño not ruled out.
The eastern tropical Pacific has already begun warming, with atmospheric coupling — the essential feedback between the ocean and the overlying atmosphere — also starting to develop, accelerating the transition.
Current ENSO-neutral conditions are expected to prevail through March-May 2026 (probability ~90%), but the outlook shifts decisively toward El Niño for May-July (probability ~58%).
A super El Niño — defined by the Oceanic Niño Index (ONI) exceeding +2.0°C above normal — carries a 22% probability for August 2026 under the ECMWF seasonal model.
La Niña, which had been influencing global weather patterns, is in the process of collapsing, with its weakening driving Pacific surface warming.
If a strong El Niño materialises, India's 2026 southwest monsoon (June-September) could face below-normal rainfall, threatening kharif crop production.
El Niño Southern Oscillation (ENSO): Mechanism and Phases
ENSO is the dominant interannual climate driver globally. It oscillates between three phases — El Niño (warm), La Niña (cool), and ENSO-Neutral — based on sea surface temperature (SST) anomalies in the central and eastern tropical Pacific.
Key Details
- Normal conditions: Trade winds blow westward across the Pacific, piling up warm water in the western Pacific. Upwelling of cold water occurs in the eastern Pacific along the South American coast.
- El Niño: Trade winds weaken or reverse; warm water sloshes eastward; SSTs in the east Pacific rise above normal. Defined when the ONI (3-month running average of SST anomaly in Niño 3.4 region) exceeds +0.5°C for five consecutive overlapping seasons.
- Super El Niño: ONI exceeds +2.0°C. Major events: 1982-83, 1997-98 (the benchmark event), 2015-16.
- La Niña: Trade winds strengthen; cold water upwelling intensifies; SSTs in east Pacific fall below normal. Associated with above-normal monsoon rainfall in India.
- ENSO Modoki: A variant where warming occurs in the central Pacific (not the east); its effect on India's monsoon differs from canonical El Niño.
The ECMWF's forecast of El Niño forming by May 2026 follows a La Niña episode, consistent with the typical ENSO oscillation pattern. The 22% super El Niño probability makes this a high-stakes event for global and Indian agriculture.
El Niño's Impact on the Indian Summer Monsoon
The Southwest Monsoon (June-September) delivers ~78% of India's annual rainfall and is the lifeline of its agrarian economy. ENSO is the single largest external modulator of monsoon variability.
Key Details
- El Niño suppresses the Indian Summer Monsoon Rainfall (ISMR) through anomalous subsidence over the Indian subcontinent driven by changes in the Walker Circulation — the east-west atmospheric overturning circulation along the equatorial Pacific.
- Historically, ~60% of strong El Niño years are associated with below-normal monsoon rainfall in India; droughts of 2002, 2009, and 2015 all occurred in El Niño years.
- However, the Indian Ocean Dipole (IOD) acts as a critical moderator: a positive IOD (warmer western Indian Ocean relative to eastern) can partially neutralise El Niño's suppressing effect. This was evident in 1997 and 2019.
- Kharif crops most vulnerable to El Niño-induced drought: rice, sugarcane, cotton, oilseeds, and maize — especially in northwest and southern peninsular India.
- The India Meteorological Department (IMD) issues long-range forecasts in April and May, incorporating ENSO and IOD signals.
A confirmed El Niño by May 2026, particularly if strong, would be a major input into IMD's June pre-monsoon forecast and would trigger contingency plans under the National Food Security Act and the Minimum Support Price (MSP) framework.
Walker Circulation and Teleconnections
The Walker Circulation is the east-west atmospheric circulation loop over the tropical Pacific. Its disruption during El Niño produces teleconnections — climate anomalies in regions far from the Pacific.
Key Details
- During El Niño: Rising air over the eastern Pacific, sinking air over the western Pacific and Indian Ocean → suppressed convection and rainfall over South Asia, Australia.
- Simultaneously, El Niño tends to produce above-normal rainfall in southern Africa, South America (Peru/Ecuador), and the southern United States.
- The term "teleconnection" refers to statistically significant correlations between climate anomalies in widely separated regions — a key concept for understanding global climate patterns.
- The Hadley Circulation (north-south) and Walker Circulation interact, influencing the strength of the ITCZ (Inter-Tropical Convergence Zone) and monsoonal systems.
The article notes that atmospheric coupling is already "unfolding" — meaning the Walker Circulation is beginning to respond to eastern Pacific warming, which is the key trigger for a full El Niño event.
- ECMWF (based in Reading, UK): world's leading operational weather forecasting centre; issues seasonal forecasts used globally.
- El Niño definition: ONI (Oceanic Niño Index) above +0.5°C for 5 consecutive overlapping 3-month periods.
- Super El Niño: ONI exceeds +2.0°C. Last occurrence: 2015-16 (peak ONI ~2.6°C).
- ECMWF probability for El Niño by May-July 2026: ~58%; super El Niño by August 2026: ~22%.
- India's southwest monsoon contributes ~78% of annual rainfall; failure has direct food security consequences.
- Niño 3.4 region: 5°N–5°S, 120°W–170°W in the central-eastern tropical Pacific — the benchmark region for ENSO monitoring.
- Positive IOD (Indian Ocean Dipole) can mitigate El Niño's negative impact on India's monsoon.
- Historical El Niño droughts in India: 1877, 1918, 2002, 2009, 2015.
- IMD long-range monsoon forecast: issued in April (first stage) and May-June (second stage update).