The El Niño Southern Oscillation is a climate phenomenon in the Pacific Ocean that happens every two to seven years. Its effects, however, are global.
However, Tamil Nadu has reported a strikingly different pattern. Recently, the IMD’s Northeast Monsoon outlook reported a neutral IOD and forecast normal to above‑normal rainfall across southern Tamil Nadu under the prevailing conditions. This year, weather agencies worldwide are tracking a supposed ‘super’ El Niño. The El Niño refers to surface waters of the Pacific Ocean off the western coast of Peru and Ecuador becoming warmer than average. In an El Niño year, India has recorded deficient rainfall and more incidence of droughts, on average. In addition to the El Niño, the Indian Ocean has its own climate driver, called the Indian Ocean dipole (IOD). The IOD is a natural phenomenon where the equatorial western Ocean experiences abnormal warming while the equatorial eastern Ocean experiences abnormal cooling. A positive IOD occurs when the western Ocean near Africa becomes warmer than the eastern Ocean near Indonesia. When an El Niño shifts global wind and pressure patterns, they can supercharge the northeast monsoon over Tamil Nadu, leading to extreme rainfall and cyclones. Tamil Nadu was hit by devastating floods While India as a whole faced a weak southwest monsoon. As monsoon winds reverse into the northeasterlies, the El Niño can strengthen moisture inflow from the Bay of Bengal. This has often resulted in frequent and heavy rains and cyclones along the Tamil Nadu coast. Scientists monitor the El Niño’s progress using satellites that measure sea surface temperature, rainfall, and trade winds, and combine the data with that from buoys, boats, deep‑water stations, and coastal radars. Together, these readings provide a 3D picture of how the ocean and the atmosphere are changing.
Typically, these waters warm by about 0.5 °C, but this year the rise has reached 2 °C — a phenomenon referred to as a ‘super’ El Niño . For example, the 2015 El Niño was one of the strongest in recent decades. Chennai recorded 1,522 mm of rain in just four days (December 1-4, 2015), more than double the normal. The possible impact in October to December 2026?
