El Niño is here, but can the Indian Ocean Dipole save India's monsoon?

The India Meteorological Department (IMD) has confirmed that El Niño conditions have developed in the equatorial Pacific Ocean, raising concerns about the impact on India's monsoon season. The weather phenomenon is often linked to below-normal rainfall, rising temperatures, and drought-like conditions in several parts of the world.

Global weather agencies, including those in the United States, had forecast the return of El Niño earlier this year. Some projections suggest its influence could extend into 2027, potentially affecting weather patterns for an extended period.

According to the IMD, the atmosphere has responded to rising sea surface temperatures in the Pacific, and the coupled ocean-atmosphere system is now displaying characteristics associated with El Niño.

How El Niño affects India's monsoon

El Niño is a naturally occurring climate pattern that develops when sea surface temperatures in the central and eastern Pacific Ocean become warmer than usual. Historically, strong El Niño events have been associated with weaker monsoon rainfall in India, leading to concerns for agriculture, water availability, and rural livelihoods.

With millions of farmers depending on the southwest monsoon for crop cultivation, any significant rainfall deficit could have widespread economic and social consequences. The phenomenon is also often linked to hotter-than-normal summers across the Indian subcontinent.

What is the Indian Ocean Dipole (IOD)?

While El Niño forms in the Pacific Ocean, meteorologists are closely watching another climate pattern that originates much closer to India — the Indian Ocean Dipole (IOD).

According to NASA, the IOD is a climate phenomenon driven by differences in sea surface temperatures between the western and eastern regions of the Indian Ocean. During a positive IOD, warmer waters accumulate in the western Indian Ocean near Africa, while cooler waters develop near Indonesia in the eastern Indian Ocean. During a negative IOD, the pattern reverses.

Scientists classify the IOD into three phases:
Positive IOD
Negative IOD
Neutral IOD

The IOD plays a crucial role in shaping rainfall and temperature patterns across countries surrounding the Indian Ocean. A positive IOD typically strengthens moisture flow towards India, increasing the likelihood of enhanced rainfall during the monsoon season.

NASA notes that a positive IOD can bring heavy rainfall to parts of East Africa while contributing to drier conditions in Australia. The phenomenon can also influence sea levels and increase the risk of coastal flooding in affected regions.

Can the Indian Ocean Dipole offset El Niño's impact?

At present, the IOD remains in a neutral phase. However, the Japan Meteorological Agency (JMA) has indicated that a positive IOD could develop later this year. The agency was among the first major weather organisations to declare the onset of El Niño.

Climate experts say it is still too early to determine the strength and timing of any positive IOD event. However, historical data suggests that a positive IOD can sometimes reduce the adverse impact of El Niño on India's monsoon.

One of the most notable examples occurred in 1997, when one of the strongest El Niño events on record coincided with a powerful positive IOD. Despite the intense El Niño, India avoided a severe monsoon deficit as the positive IOD helped balance its effects.

What lies ahead for India's monsoon?

While the possibility of a positive Indian Ocean Dipole offers some hope, weather experts caution against assuming it will guarantee normal or above-normal rainfall. The extent to which it can offset El Niño depends on when it develops and how strong it becomes during the monsoon season.

For now, meteorologists will continue to monitor both climate systems closely, as the interaction between El Niño and the Indian Ocean Dipole could play a key role in determining the fate of India's monsoon in the months ahead.