UPSC Notes

El Niño-Southern Oscillation (ENSO) and Indian Monsoon

PYQs

10

Articles

2

Momentum

27

Phase IFoundation

Background

Overview

El Niño significantly influences rainfall patterns, leading to droughts or floods, impacting agriculture, water security, and the economy, making its understanding crucial for national policy planning and disaster preparedness.

El Niño-Southern Oscillation (ENSO) is a recurring climate pattern involving changes in the temperature of waters in the central and eastern tropical Pacific Ocean, coupled with changes in the atmosphere. It significantly influences global weather patterns, including the Indian monsoon, often leading to extreme weather events.

Phase IIStatic core

Facts & tables

Key facts

Strengthening El Niño Conditions

Moderate El Niño conditions are expected to strengthen through the remaining part of the Southwest monsoon.

Impact on Northeast Monsoon

El Niño is usually favourable for enhanced rainfall during the Northeast monsoon, as observed in 2015 when Chennai experienced a deluge.

Complex Climatic Interplay

Northeast monsoon behaviour is shaped by a complex interplay of atmospheric and oceanic conditions, not solely by El Niño.

Role of Indian Ocean Dipole (IOD)

Neutral IOD conditions are likely to persist, but a positive IOD may develop, potentially countering the impact of El Niño.

Mechanism

Associated with warming of the Central Equatorial Pacific Ocean.

Monsoon Impact

Typically leads to suppressed monsoon rains over India, often resulting in drought-like conditions.

Forecasting Challenge

Challenges weather departments in predicting the extent of monsoon shortfall.

Consequences

Its strengthening can threaten soil moisture and reservoir recharge in India.

Reference table

Static syllabus anchors

TypeReference
Conceptual areaClimatology
Conceptual areaOceanography
Conceptual areaGlobal Climate Phenomena

Reference table

Institutions & roles

BodyRole
India Meteorological Department (IMD)Monitors
Regional Meteorological CentreMonitors
Phase IIIExam lens

Prelims angle

Overview

Prelims angle: Multi-statement analysis

Prelims angle: Conceptual understanding

Quick revision

  • ENSO: Pacific Ocean temperature changes affecting global weather.
  • Impact on Indian Monsoon: often linked to enhanced Northeast Monsoon rainfall.
  • Complex interaction with IOD (Indian Ocean Dipole).
  • Crucial for agricultural planning and water resource management.
  • Monitored by IMD for forecasts and preparedness.

High-confidence PYQs

Topic timeline

ClimatologyOceanographyGlobal Climate Phenomena

How monsoon ready is Chennai?

02 Aug 2026 · El Niño is a major climate driver impacting the Indian monsoon, particularly the Northeast monsoon, often leading to increased rainfall. Its effects are modulated by other phenomena like the Indian Ocean Dipole, creating complex and uncertain weather patterns.

Read article

Season’s end: On the India Meteorological Department forecasts, rainfall deficit

02 Oct 2026 · El Niño, a warming of the Pacific, is a key global climate driver often linked to weaker Indian monsoons, posing significant challenges for rainfall prediction and impacting India's agriculture and water resources.

Read article

Related topics

Practice writing on this topic

UPSC has asked 10 linked questions on El Niño-Southern Oscillation (ENSO) and Indian Monsoon in Mains. Write an answer to one — and get it evaluated.

UPSC Prelims PYQs on El Niño-Southern Oscillation (ENSO) and Indian Monsoon

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