CHENNAI: Tamil Nadu could face a mix of floods, water scarcity and heatwaves as a strong El Nino develops through late 2026 and persists into early 2027, the state’s expert advisory committee has warned, stressing that the phenomenon cannot be treated simply as a drought signal.
Revenue and Disaster Management Minister K A Sengottaiyan handed over the committee’s report to Chief Minister C Joseph Vijay at a monsoon preparedness review meeting chaired by the CM on Monday.
The panel has recommended a multi-hazard preparedness strategy covering floods, water scarcity, heatwaves, cyclones, agriculture, fisheries, health and critical infrastructure.
The committee has proposed three implementation windows: before the 2026 northeast monsoon, before summer 2027 and over the following three to five years. As of August 29, the Nino 3.4 sea-surface temperature anomaly stood at +2.20°C, indicating strong El Nino conditions. The August outlook assigned a 100% probability of El Nino from August-October 2026 through February-April 2027.
The timing is significant as the projected peak overlaps with Tamil Nadu’s northeast monsoon, its principal rainy season. However, the committee noted that historical data do not show a consistent suppression of northeast monsoon rainfall during El Nino years.
An IMD assessment covering 1940-2021 found that northeast monsoon rainfall over the region during El Nino years was excess in 28% of the years, normal in 57% and deficient in only 15%.
The state’s experience also showd variability. During the strong 1997-98 El Nino, TN received 52% excess northeast monsoon rainfall in 1997. According to the IMD, in 2005, the state recorded 79% excess rainfall during October-December, with multiple depressions and cyclonic systems triggering repeated heavy-rain episodes.
The 2015-16 El Nino produced both extremes, according to the IMD report. Chennai received 1,416.8 mm between November 1 and December 5, 2015, against a normal of 408.4 mm, including 275 mm on December 1, which triggered unprecedented flooding.
The following year, however, Tamil Nadu received only 168.3 mm, a 62% deficit. As many as 13,305 of 16,682 revenue villages were affected by drought, and all 32 districts were declared drought-affected.The 2023-24 El Nino also coincided with extreme rainfall.
During Cyclone Michaung, Chennai received 45.82 cm between December 1 and 4, against a December normal of 15.74 cm. For 2026, the ECMWF seasonal forecast indicates above-normal precipitation over Tamil Nadu during October-December.
Against this backdrop, the committee has recommended frequent monitoring of reservoir storage and inflows, desilting of waterways, district-level flood-risk mapping, stronger early-warning systems and heat-health preparedness. It has also called for probabilities, including the likelihood of rainfall exceeding 100 mm, and temperatures above 40°C.
