Special Topic – Indian Monsoon
Page 3 | Impact of El Niño on Indian Monsoon

Introduction:
El Niño events have a significant influence on the strength, onset, and distribution of the Indian monsoon. Historically, many El Niño years have coincided with below-normal rainfall and drought-like conditions in India.

 Why El Niño Weakens the Indian Monsoon

During El Niño, warming of the central and eastern Pacific Ocean weakens the Walker Circulation. As a result, convection shifts away from the Indian Ocean region, leading to a weaker low-pressure system over the Indian subcontinent and reduced monsoon winds.

Major Impacts on Monsoon Behaviour

• Below-normal rainfall during the southwest monsoon
• Delayed onset of monsoon over Kerala
• Long dry spells or break monsoon conditions
• Uneven spatial distribution of rainfall

 Regional Variations in Impact

• Central and north-western India often face rainfall deficits
• Peninsular India experiences high rainfall variability
• Reservoir inflows and river discharge reduce significantly
• Some eastern and southern regions may receive near-normal rainfall

 Historical Evidence

• 2002: One of the worst droughts linked to El Niño
• 2009: National rainfall deficit affected agriculture
• 2015: El Niño combined with heat stress reduced crop output

 Limits of El Niño Influence

El Niño does not always lead to drought. Other factors such as the Indian Ocean Dipole (IOD), local sea surface temperatures, and atmospheric conditions can offset or amplify its impact on the Indian monsoon.

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🎯 Key Insight:
El Niño is a major global driver of monsoon variability, but its impact on India depends on the interaction of multiple climatic and regional factors.