El Niño-Southern Oscillation (ENSO) and Indian Monsoon
El Niño is the warm phase of the El Niño-Southern Oscillation (ENSO) cycle, characterised by anomalous warming of sea surface temperatures (SSTs) in the central and eastern equatorial Pacific Ocean. The coupled ocean-atmosphere system oscillates between the warm (El Niño) and cold (La Niña) phases on an irregular 2–7 year cycle.
- During El Niño, the Walker Circulation weakens: warm water shifts eastward in the Pacific, reducing convective activity over the Indian Ocean and suppressing monsoon rainfall over India and the subcontinent.
- El Niño years historically correlate with below-normal Indian monsoon rainfall; approximately 60% of El Niño events are associated with deficient monsoon (below 90% of long-period average).
- India's long-period average (LPA) for monsoon rainfall is approximately 87 cm over June–September.
- La Niña (cold phase) typically enhances Indian monsoon rainfall.
- Monitored by NOAA (USA) and the Bureau of Meteorology (Australia); declared when the Oceanic Niño Index (ONI) exceeds +0.5°C for at least five consecutive overlapping three-month periods.
- NOAA declared El Niño on June 11, 2026, with projections of the event persisting into the Northern Hemisphere winter of 2026–27 and potentially becoming a very strong event.
● Tracked since March 13, 2026 · last seen September 09, 2026 · updates as the daily brief publishes
20 Aug '26
El Niño, Food Inflation, and Why Irrigation Coverage Matters for Rural Resilience
Economics
28 Jul '26
India's 2026 Monsoon Shows Sharp Regional Swings as National Deficit Hits 16%
Environment & Ecology
30 Jun '26
India's June 2026 Monsoon Deficit: El Niño, MJO, and the Physics of a Weak Monsoon
Geography
15 Jun '26
Kharif 2026 Sowing Off to Slow Start as El Niño Weakens Monsoon Outlook
Environment & Ecology
29 May '26
El Niño Onset Pushes India's 2026 Monsoon Forecast to Potential 11-Year Low
Environment & Ecology
22 Apr '26
RBI's Inflation Risk Assessment: Energy Prices, West Asia Conflict, and El Niño
Economics
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