El Niño 3.4 region records highest ever temperature, signalling historic ENSO event

The El Niño 3.4 region in the equatorial Pacific has recorded its highest absolute temperature ever measured, adding a worrying data point to what scientists already expect to be one of the most intense El Niño events in 75 years. On 11 June, the US National Oceanic and Atmospheric Administration (NOAA) officially declared the arrival of El Niño, projecting a 65% probability of a “very strong” phase and a progressive intensification toward winter.

The El Niño-Southern Oscillation (ENSO) is a cyclical climate phenomenon that exerts major influence on global weather. During its warm phase, known as El Niño, a lack of trade winds allows sea surface temperatures in the central and eastern Pacific to soar. This disrupts atmospheric circulation worldwide: some regions face severe drought while others are struck by torrential rain, as explained by Spain’s State Meteorological Agency (AEMET).

While the absolute temperature record is striking, researchers caution that El Niño intensity is measured by the anomaly between the Niño-3.4 region and surrounding waters, which remains relatively low for now. The rapid onset, however, is consistent with expectations for a powerful event. The current year already holds the record for the hottest 12-month period from April 2025 to March 2026.

The 2023–24 El Niño, ranked among the five strongest on record, contributed to 2024 becoming the hottest year globally. Historic “super Niño” events in 1982–83, 1997–98 and 2015–16 each caused severe global impacts, including an estimated 24,000 fatalities and economic losses exceeding US$30 billion. Although forecasting and preparation have significantly improved, the scale of this developing event raises concerns about similar consequences.