El Niño emerges in Pacific Ocean, to intensify during SW monsoon season: IMD

The India Meteorological Department (IMD) confirmed the emergence of El Niño conditions over the equatorial Pacific Ocean in June 2026, with sea surface temp...

What Happened

The India Meteorological Department (IMD) confirmed the emergence of El Niño conditions over the equatorial Pacific Ocean in June 2026, with sea surface temperatures (SSTs) showing a significant warming trend in the central and eastern equatorial Pacific.
IMD warned that El Niño conditions are likely to intensify through the Southwest Monsoon season (June–September 2026), with a 92% probability of El Niño conditions prevailing during the monsoon season.
The 2026 monsoon season is projected to receive around 800 mm of rainfall — below the Long Period Average (LPA), raising concerns about agricultural output for the kharif crop season.
The probability of a deficient monsoon season (rainfall below 90% of LPA) stands at 35% — more than double the long-term climatological probability of 16%, reflecting elevated risk.
NOAA forecasts suggest the 2026 El Niño could intensify into a very strong event, with some analyses indicating it may rival or exceed the strength of the 1997–98 El Niño, which was associated with drought and famine conditions in large parts of South and Southeast Asia.
Approximately 60% of Indian farmers depend on monsoon rainfall for kharif crop irrigation, making the IMD alert directly relevant to India's food security and rural economy.

Static Topic Bridges

El Niño–Southern Oscillation (ENSO): The Pacific Climate Driver

El Niño–Southern Oscillation (ENSO) is a naturally recurring climate pattern that involves the coupling of oceanic and atmospheric conditions across the tropical Pacific Ocean. It has three phases: El Niño (warm phase), La Niña (cool phase), and ENSO-neutral. Under normal conditions, easterly trade winds blow from South America towards Asia and Australia, pushing warm surface water westward and causing cool water to upwell in the eastern Pacific (off the coast of Peru and Ecuador). This upwelling maintains lower sea surface temperatures in the east and warm pool conditions in the west, supporting the Walker Circulation — the east-west atmospheric convection loop over the equatorial Pacific.

During El Niño: trade winds weaken or reverse, warm water spreads eastward across the Pacific, SSTs in the central and eastern equatorial Pacific rise by 0.5°C or more above the baseline (the Niño 3.4 index is the standard measurement), and the Walker Circulation weakens or reverses.
During La Niña: trade winds intensify, cooler water upwells in the eastern Pacific, the warm pool in the western Pacific intensifies, and rainfall in South and Southeast Asia is typically enhanced.
ENSO events typically develop between April and June and peak between November and January; they persist for 9–12 months on average but can last longer in strong events.
ENSO monitoring relies on SST anomalies in four Pacific ocean regions (Niño 1+2, Niño 3, Niño 3.4, Niño 4), atmospheric pressure differences between Darwin and Tahiti (the Southern Oscillation Index — SOI), and upper-ocean heat content.

Connection to this news: The 2026 El Niño developed in the central and eastern equatorial Pacific from La Niña-neutral conditions, with SST warming accelerating through April–June 2026 — placing the event's emergence precisely at the onset of India's southwest monsoon season.

Walker Circulation and Its Role in Monsoon Regulation

The Walker Circulation is an atmospheric convection system driven by the temperature contrast between the warm western Pacific and the cooler eastern Pacific. Warm air rises over the western Pacific and Indonesia (where the warm pool is located), moves eastward at upper levels, descends over the cooler eastern Pacific, and returns westward at the surface as the trade winds. This circulation is one of the key atmospheric teleconnections that links Pacific SST anomalies to rainfall patterns across the globe, including the Indian subcontinent. A weakened Walker Circulation during El Niño reduces subsidence over the Indian region and diminishes the thermal gradient that drives monsoon onset.

During El Niño, the Walker Circulation's rising branch shifts eastward (from the western Pacific towards the date line), reducing the ascending motion over the Indian Ocean and Indian subcontinent.
This suppresses convective activity over India, weakening the low-level jet stream that delivers moisture from the Arabian Sea into the Indian peninsula — the primary mechanism for southwest monsoon rainfall.
The Southern Oscillation Index (SOI) — measuring atmospheric pressure difference between Tahiti and Darwin — becomes negative during El Niño, serving as a real-time proxy for the Walker Circulation's weakening.
Historical analysis: of the 26 major drought years in India between 1871 and 2022, approximately 65% were associated with El Niño conditions.

Connection to this news: The IMD's concern is precisely that the 2026 El Niño is developing during the southwest monsoon onset, when the Walker Circulation's weakening exerts its maximum negative influence on monsoon moisture transport — a historically high-risk combination.

India Meteorological Department (IMD) and Monsoon Forecasting

The IMD, established in 1875 under the Ministry of Earth Sciences, is India's national meteorological service responsible for weather forecasting, climate monitoring, and natural disaster early warning. It issues the official Long Range Forecast (LRF) for the southwest monsoon (June–September) in stages: the first stage forecast is issued in April, the second stage in May/June. The LRF uses a multi-model ensemble (MME) approach incorporating global climate models, statistical models, and ENSO state as the dominant predictor. The Long Period Average (LPA) for all-India southwest monsoon rainfall is 87 cm (870 mm) for the period 1971–2020.

IMD's LPA for southwest monsoon (JJAS): 870 mm (1971–2020 base period)
A "deficient" monsoon is defined as rainfall below 90% of LPA (i.e., below 783 mm).
A "normal" monsoon: 96–104% of LPA; "below normal": 90–95%; "above normal": 105–110%; "excess": above 110%.
The IMD uses 16 global climate models within its MME framework; ENSO state is the single most important predictor for all-India monsoon rainfall.
IMD also monitors the Indian Ocean Dipole (IOD) — another oceanic teleconnection; a positive IOD can partially offset El Niño's negative impact on the monsoon.

Connection to this news: IMD's June 2026 alert, placing the probability of a deficient season at 35% (more than double the climatological base rate of 16%), reflects direct incorporation of the El Niño signal into its probabilistic forecast framework — a significant operational warning for agricultural planners and disaster managers.

El Niño and the Indian Monsoon: Historical Correlation and Agricultural Risk

The statistical relationship between El Niño and Indian summer monsoon rainfall (ISMR) has been studied since the 1890s, when Henry Blanford and Henry Walker first identified the teleconnection. Historically, strong El Niño events (Niño 3.4 SST anomaly > +1.5°C) are associated with below-normal or deficient monsoon rainfall over India, particularly over the central and peninsular India regions. However, the relationship is not deterministic: the Indian Ocean Dipole (IOD), Eurasian snow cover, and Madden–Julian Oscillation (MJO) can modulate the El Niño signal, sometimes producing near-normal monsoons even in El Niño years (as in 2019). The 1987, 1997, 2002, 2009, and 2015 El Niño events were all associated with significant monsoon deficits in India.

Historical drought–El Niño association: ~65% of major Indian drought years coincide with El Niño conditions.
El Niño years with significant rainfall deficit: 1987 (deficient), 2002 (deficient), 2009 (deficient), 2015 (below normal in many regions).
El Niño year with near-normal monsoon despite strong event: 2023 (positive IOD partly offset El Niño impact).
Agricultural exposure: kharif crops (paddy, soybean, groundnut, pulses, cotton) covering approximately 110–120 million hectares are directly dependent on monsoon rainfall.
A 10% monsoon deficit can reduce kharif foodgrain output by 5–8%, with knock-on effects on rural incomes and food inflation.

Connection to this news: The IMD's 35% probability of a deficient monsoon in 2026 — driven by the emerging El Niño — directly translates into risk for India's kharif season agricultural output, food price stability, rural incomes, and fiscal management (via potential higher food subsidy costs and crop insurance payouts).

Key Facts & Data

Probability of El Niño conditions during SW Monsoon 2026: 92% (IMD)
Projected 2026 monsoon rainfall: ~800 mm (below LPA of 870 mm)
Probability of deficient monsoon (< 90% of LPA): 35% (vs. long-term average of 16%)
Long Period Average (LPA) for southwest monsoon: 870 mm (1971–2020 base)
Definition of deficient monsoon: rainfall below 783 mm (< 90% of LPA)
Proportion of Indian farmers dependent on monsoon rainfall: ~60%
IMD El Niño threshold: SST anomaly in Niño 3.4 region of +0.5°C or more for ≥ 5 consecutive overlapping seasons
Historical El Niño–India drought association: ~65% of major drought years linked to El Niño
2026 El Niño intensity assessment (NOAA): potentially very strong; may rival the 1997–98 event
Key monitoring indices: Niño 3.4 SST anomaly, Southern Oscillation Index (SOI), Indian Ocean Dipole (IOD)