El Niño to dominate India’s post-monsoon season; neutral IOD raises rainfall concerns

India could face a largely dry post-monsoon season as a strengthening El Niño continues to influence global weather patterns, while the Indian Ocean Dipole (IOD) is forecast to remain neutral during the northeast monsoon season.

According to the India Meteorological Department (IMD), strong El Niño conditions are currently prevailing over the equatorial Pacific Ocean, with sea surface temperatures significantly above normal across the east-central and eastern Pacific. IMD’s Monsoon Mission Coupled Forecast System (MMCFS), along with other global climate models, indicates that El Niño is likely to strengthen further through the end of 2026.

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What does a neutral IOD mean?

The Indian Ocean Dipole is a climate phenomenon driven by differences in sea surface temperatures between the western and eastern tropical Indian Ocean. A positive IOD, in which waters near Africa are warmer than normal while those near Indonesia are cooler, can support rainfall over parts of the Indian subcontinent.

However, the IMD expects the IOD to remain neutral during the northeast monsoon season. In a neutral phase, there is no strong temperature contrast across the Indian Ocean to provide an additional rainfall-supporting influence.

This means the neutral IOD is not expected to cancel out the influence of El Niño. Instead, the Pacific climate pattern is likely to remain the stronger signal affecting India's weather during the coming months.

Post-monsoon rainfall outlook

The October-December period is particularly important for southern peninsular India, where the northeast monsoon contributes a substantial share of annual rainfall. Tamil Nadu, Puducherry and parts of Andhra Pradesh, Kerala and Karnataka depend significantly on this season.

El Niño can alter atmospheric circulation and influence rainfall patterns far beyond the Pacific Ocean. However, its impact is not uniform across India, and the presence of El Niño does not automatically mean that every part of the country will experience deficient rainfall.

The latest outlook comes after India ended the 2026 southwest monsoon with rainfall about 13 per cent below normal. The season delivered roughly 87 per cent of the long-period average, making it one of the weaker monsoon seasons in recent years.

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What lies ahead

With El Niño strengthening and no positive IOD expected to develop, the Indian Ocean is unlikely to provide a significant counter-effect to the Pacific warming pattern.

The IMD's assessment therefore points to El Niño remaining the dominant climate signal through the post-monsoon period. At the same time, regional variations are expected, meaning some parts of India could still receive normal or above-normal rainfall despite the broader climate pattern.

The coming months will be particularly important for southern states dependent on northeast monsoon rainfall, as well as for agriculture and water resources in areas already affected by the deficient southwest monsoon.