Defining El Niño signature may emerge by next month, says Japan-based scientist

Scientists tracking the El Niño–Southern Oscillation (ENSO) system have indicated that a defining El Niño signature in the tropical Pacific Ocean is likely t...

What Happened

Scientists tracking the El Niño–Southern Oscillation (ENSO) system have indicated that a defining El Niño signature in the tropical Pacific Ocean is likely to emerge by May–June 2026, with the event expected to strengthen through the second half of the year and potentially persist into early 2027.
Japan-based researchers tracking the phenomenon note that the redistribution of heat energy associated with El Niño development is already being felt beyond the Pacific, including over the Indian Ocean and Indian subcontinent.
The India Meteorological Department (IMD), in its first long-range forecast issued on April 13, 2026, projected the 2026 southwest monsoon at 92% of the Long Period Average (LPA) — classified as "below normal."
The IMD has attributed the likely rainfall deficit primarily to the emergence of El Niño conditions in the equatorial Pacific Ocean during the second half of the southwest monsoon season (June–September).
Forecasting agencies including ECMWF and NOAA's Climate Prediction Center have assigned a 61% probability to El Niño conditions establishing by mid-2026, with some models projecting a "super El Niño" rivalling the intensity of the 1997–98 and 2015–16 events.

Static Topic Bridges

El Niño–Southern Oscillation (ENSO)

ENSO is the most significant driver of year-to-year climate variability on Earth. It refers to the coupled ocean-atmosphere system over the tropical Pacific, which alternates between warming (El Niño), cooling (La Niña), and neutral phases.

El Niño is characterised by anomalous warming of sea surface temperatures (SSTs) in the central and eastern equatorial Pacific Ocean (specifically the Niño 3.4 region).
The atmospheric component is the Southern Oscillation — a see-saw in atmospheric pressure between the eastern Pacific (Tahiti) and the western Pacific/Indian Ocean (Darwin, Australia), measured by the Southern Oscillation Index (SOI).
During El Niño, the Walker Circulation weakens or reverses: normally, strong easterly trade winds push warm surface water westward; when they weaken, warm water spreads eastward, suppressing convection over the western Pacific and Indian Ocean.
El Niño events typically last 9–12 months; "super El Niño" events (e.g., 1997–98, 2015–16) involve SST anomalies exceeding +2°C over the Niño 3.4 region.
The ENSO cycle (2–7 years) is monitored using SST indices, equatorial Pacific thermocline depth, trade wind strength, and outgoing longwave radiation.

Connection to this news: The 2026 event is developing through the same mechanism: warming SSTs in the central Pacific, weakening trade winds, and a shift in deep atmospheric convection — which reduces moisture transport into the Indian subcontinent during the monsoon season.

El Niño–Indian Monsoon Teleconnection

The link between El Niño and Indian monsoon deficits is one of the best-studied climate teleconnections in the world. Historically, about 60% of strong El Niño years have coincided with below-normal or deficient monsoon rainfall over India.

The mechanism: warming of the equatorial Pacific shifts the Walker Circulation's ascending branch eastward, reducing moisture uplift over the Bay of Bengal and weakening the monsoon trough.
The Hadley Cell also strengthens during El Niño, creating anomalous subsidence (sinking air) over South Asia — further suppressing convection and rainfall.
The Indian Ocean Dipole (IOD) modulates this teleconnection: a positive IOD (warmer western Indian Ocean relative to eastern) can partially counteract El Niño's drying effect on India.
Notable El Niño-linked drought years in India include 1987, 2002, and 2009; the 2023 monsoon (moderate El Niño) recorded rainfall at 94% of LPA.
IMD's April 2026 forecast of 92% LPA translates to an expected deficit of roughly 8%, which, if uniformly distributed, could reduce kharif agricultural output significantly.

Connection to this news: The forecast is directly grounded in this teleconnection: IMD's models flagged the emerging El Niño as the primary driver of the projected below-normal monsoon, with regional exceptions expected in the extreme north, extreme west, northeast, and northern south peninsula.

Walker Circulation and Its Role in Monsoon Disruption

The Walker Circulation is a large-scale east–west atmospheric circulation pattern along the equatorial belt, driven by the temperature gradient between the warm western Pacific and the cooler eastern Pacific.

Normal Walker Circulation: Warm, moist air rises over the western Pacific (Indonesia–Philippines), moves eastward aloft, descends over the cold eastern Pacific (Peru coast), and returns westward at the surface as trade winds.
An active Walker Circulation energises the Indian Ocean branch of the circulation, which in turn drives the southwest monsoon.
During El Niño, the Walker Circulation slackens: the ascending branch shifts east toward the central Pacific, robbing the Indian Ocean branch of energy and reducing monsoon intensity.
The weakening is detectable through the Southern Oscillation Index (SOI): strongly negative SOI values (pressure high in Darwin, low in Tahiti) signal El Niño.

Connection to this news: Scientists tracking ENSO in 2026 are observing exactly this pattern — a weakening and eastward displacement of the Walker Circulation — which aligns with the IMD's forecast of a below-normal monsoon.

Impact of Monsoon Deficit on India's Agriculture and Economy

The southwest monsoon (June–September) delivers approximately 70–80% of India's annual rainfall. Over 600 million people depend on it directly or indirectly.

Approximately 60% of India's net sown area is rain-fed; a 1% drop in monsoon rainfall can reduce agricultural GDP by an estimated 0.4%.
Key kharif crops vulnerable to monsoon deficit: paddy (rice), pulses (tur/urad/moong), soybean, cotton, and sugarcane.
Below-normal monsoon raises food inflation risk, especially for vegetables, pulses, and edible oils — items with inelastic demand.
The government typically activates contingency plans: crop insurance (Pradhan Mantri Fasal Bima Yojana), NREGA for rural employment, and buffer stock releases to stabilise prices.
The 2026 below-normal monsoon forecast gains additional significance in the context of the government's wheat export push (after a surplus season) — if kharif output disappoints, domestic food security concerns could reassert themselves.

Connection to this news: The El Niño forecast is not merely a meteorological event — it is a policy trigger. A deficit monsoon year typically prompts revisions to procurement targets, export policies, and social protection spending.

Key Facts & Data

IMD's April 13, 2026 first long-range forecast: 2026 southwest monsoon at 92% of LPA — "below normal."
LPA (Long Period Average) for India's southwest monsoon: approximately 87 cm (868.6 mm).
El Niño threshold: SST anomaly of +0.5°C or more in the Niño 3.4 region (5°N–5°S, 170°W–120°W) for five consecutive overlapping three-month periods.
Probability of El Niño establishing by mid-2026: ~61% (NOAA, ECMWF estimates).
Historical strong El Niño years: 1972–73, 1982–83, 1997–98, 2015–16 — all coincided with significant Indian monsoon deficits.
The 2026 event, if it reaches "super El Niño" intensity, would be among the strongest in recorded history.
IOD (Indian Ocean Dipole): A positive IOD can partially counteract El Niño's negative impact on Indian monsoon — current IOD status is being closely monitored.
Approximately 60% of India's farmers depend fully on monsoon rainfall for the kharif season.
Regions projected to be least affected: extreme north, extreme west, northeast, and northern south peninsula.
Walker Circulation monitoring metric: Southern Oscillation Index (SOI) — negative values indicate El Niño tendency.