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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.

Key details

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.