Influence of El Niño/La Niña on the Indian Monsoon

At a Glance

• El Niño Usually weak monsoon, drought risk
• La Niña Usually strong monsoon
• Offset Positive Indian Ocean Dipole
• Exception year 1997
• Forecaster India Meteorological Department
• Exam link UPSC Prelims, Geography: Climatology

Where Does It Fit?

This topic follows the topic on El Niño, La Niña and the Dipole and applies them to India. It connects the macro on climatology to the later macro on the physical geography of India, where the monsoon is described. Previous topic: El Niño and La Niña: ENSO and the Indian Ocean Dipole Effect. Next topic: World Climate Types (Köppen Classification): Equatorial, Monsoon, Savanna, Desert, Mediterranean, Temperate and Polar Climates.

How Does El Niño Affect the Indian Monsoon?

The link was found by Gilbert Walker. In an El Niño year, the shift of the Walker Circulation brings sinking air to the Indian region, and the south-west monsoon tends to be weak, as in Monsoon Mechanism: Traditional and Contemporary Theories (Air Mass Theory, Jet Stream Theory). The droughts of 2002, 2009, 2014 and 2015 occurred in El Niño years, with the all-India rainfall at about 81 per cent, 78 per cent, 88 per cent and 86 per cent of the long period average, respectively. In 2023 too the monsoon ended at about 94 per cent of the average, with a dry August. But the link is not perfect. Not all El Niño years are droughts, and 1997, a very strong El Niño, had a normal monsoon because a positive Indian Ocean Dipole, a warm western Indian Ocean, offset it. Some droughts happen without an El Niño. The monsoon is also helped or hurt by the Indian Ocean Dipole, the Eurasian snow cover and the Madden-Julian Oscillation, so forecasters use ENSO as one of the main predictors, not the only one.

As an analytical point, the effect of a weak monsoon on the economy is today smaller than before, because agriculture is a smaller share of the national income, there is a large buffer stock of food grains and irrigation covers more land, but rural income and food price inflation, especially in pulses, vegetables and cereals, are still exposed.

How Have Recent El Niño and La Niña Years Compared?

The long-period average (LPA) of India’s monsoon rainfall is about 87 cm. The percentages are from official figures of the India Meteorological Department, and they are rounded here, so the exact values should be checked.

Why Is the Link Not Perfect?

• Not every El Niño brings drought: many, but not all, of India’s droughts have coincided with El Niño, and the monsoon of 1997 stayed normal in a strong El Niño year.
• The Indian Ocean Dipole: a positive dipole, with warmer water in the west of the Indian Ocean, brings extra rain to India and can offset El Niño. A negative dipole can make the monsoon worse in an El Niño year.
• Timing and strength: an El Niño that develops early in the year affects the monsoon more than one that develops late.
• Other factors: snow cover over Eurasia, the Madden-Julian Oscillation, the Atlantic and local conditions also matter.

As an analytical point, ENSO is the most important known predictor of the monsoon, and the India Meteorological Department follows ENSO and IOD to issue its forecasts. The wider mechanism of the monsoon is in Monsoon Mechanism: Traditional and Contemporary Theories (Air Mass Theory, Jet Stream Theory), and its impact is further in Impact of El Niño and La Niña on the Indian Monsoon.

How Do El Niño and La Niña Affect Indian Farming and Policy?

A weak monsoon reduces the sowing of kharif crops such as rice, pulses, oilseeds and cotton, and raises food prices, while a good monsoon lifts output and rural income. The government watches the forecasts closely and prepares measures such as buffer stocks, contingency crop plans, export controls and relief for drought-hit districts. In a La Niña year, the heavy rain can cause floods in parts of the country, such as Assam, Bihar and the Western Ghats. The India Meteorological Department issues a long-range forecast in April, updated in May and June, with ENSO and IOD conditions as inputs.

Why Is This Topic Important?

• Recurring theme El Niño is asked every year
• India Monsoon and food prices
• Current affairs Strong event in 2026

What Came Next?

The next topic describes the climate types of the world according to the Köppen classification. Next topic: World Climate Types (Köppen Classification): Equatorial, Monsoon, Savanna, Desert, Mediterranean, Temperate and Polar Climates.

Key People and Terms

• ENSO El Niño-Southern Oscillation
• ONI Oceanic Niño Index
• Niño 3.4 Pacific region used to monitor ENSO
• Bjerknes feedback Self-reinforcing ocean-atmosphere loop
• Indian Ocean Dipole East-west temperature difference in the Indian Ocean
• Teleconnection Distant weather link

Exam Corner

Mains Angle

Questions ask for effects and the Indian link. These points add depth.

• Cause Weak winds and warm east
• India Weaker monsoon, but offset by IOD
• Economy Food inflation and policy response