Super El Niño to raise temperature by 3°C in TN next year

CHENNAI: Tamil Nadu could face a hotter than normal summer in 2027 as an exceptionally strong El Niño gathers pace in the Pacific Ocean, raising concerns over more frequent heatwaves, higher temperatures and mounting pressure on water resources. However, scientists caution that the extent of its impact on the State will depend on regional weather conditions and the combined influence of global warming.

The World Meteorological Organization (WMO), in its climate update released on October 8, forecast that sea surface temperatures in the central and eastern tropical Pacific could reach around 3.7°C above normal during October to December 2026, with the phenomenon expected to peak around December.

VR Durai, senior atmospheric scientist, Regional Meteorological Centre (RMC), Chennai, told DT Next that the projected warming should not be attributed to El Niño alone. “Climate change and the long term warming of the oceans are also contributing to the unusually high temperatures in the Pacific, and not by El Niño alone,” he opined. “We must also account for the warming caused by climate change. The oceans are becoming warmer, and this additional heat is contributing to the present situation.”

He pointed out that 2024 was the warmest year in recorded global temperature, reflecting the ocean warming trend. Such background warming can amplify the El Niño Temperature rise.

Durai also stressed the importance of using appropriate ocean temperature indices and long term observations to assess the intensity of the phenomenon. NOAA’s Relative Oceanic Niño Index (RONI) is used for monitoring and classifying El Niño and La Niña conditions, taking into account tropical Pacific temperatures relative to the broader tropical oceans.

Tamil Nadu could experience higher summer temperatures if the strong El Niño coincides with persistent hot and dry conditions over the region. Durai said that a rise of up to 3°C above normal (Summer temperatures in parts of the State can reach 42°C to 42.5°C)

El Niño could influence cloud formation and atmospheric circulation, potentially favouring clearer skies and greater solar heating in some regions. But it does not automatically produce heatwaves everywhere, and its influence on TN’s summer weather cannot be determined from Pacific Ocean temperatures alone.

Meanwhile, TN’s expert committee monitoring the Super El Niño phenomenon has cautioned the European Centre for Medium Range Weather Forecasts’ seasonal forecast system, issued in August 2026, indicated the possibility of above normal precipitation over Tamil Nadu and neighbouring southern regions during October December, with anomalies of around 50-200 mm in parts of the region.

Experts also cautioned that seasonal model projections should not be interpreted as predictions of individual rainfall events. Even if seasonal rainfall was normal or above normal, the State could still experience dry spells, intense short duration rainfall or cyclones.

The committee has recommended a multi hazard preparedness strategy rather than planning for a single outcome. This is particularly important because the same climate system can produce contrasting effects across regions and seasons.

An expert associated with the State’s monitoring committee told DT Next that assessment would be prepared after the northeast monsoon concludes. The committee would examine water storage levels in reservoirs, lakes and ponds before recommending further measures, if necessary.

If available storage proves inadequate to meet future demand, the committee may advise the government to consider restricting non essential water use, including water intensive car washing services and irrigation systems in parks, and regulating industrial water consumption where appropriate.

With the Pacific warming rapidly and the 2027 summer still several months away, experts say continued monitoring of ocean conditions, rainfall forecasts and reservoir levels will be crucial.

For Tamil Nadu, the challenge will be to prepare simultaneously for possible extreme heat, uneven rainfall and pressure on water supplies.

El Niño peaks

1) 2026–2027: +3.05°C to +3.08°C

Forecasted to peak up to +4.0°C

Strongest on record

Smashed previous daily and monthly zone records weeks before its expected peak

2) 2015–2016: +2.6°C

Caused the Chennai flood

3) 1997–1998: +2.3°C

Frequently cited as the benchmark ‘Super El Nino’ of the 20th Century

4) 1982–1983: +2.2°C

First ‘very strong’ event captured by modern satellite

5) 2023–2024: +2.0°C

2024 warmest year on record

6) 1972–1973: +2.1°C

Collapsed global marine productivity and fisheries

El Niño classification by temperature

Weak: +0.5°C to +0.9°C anomaly

Moderate: +1.0°C to +1.4°C anomaly

Strong: +1.5°C to +1.9°C anomaly

Very strong (Super): +2.0°C or greater anomaly