A powerful El Niño is intensifying in the Pacific after the sea-surface temperature anomaly in the Niño 3.4 region reached 3.11 degrees Celsius on Sept. 21, according to data reported by Tiempo.com. That surpassed the previous record of 3.08°C, recorded on Nov. 18, 2015, during the 2015-16 El Niño.

The reading came months before the period when the strongest El Niño events typically reach their peak. Models cited by Tiempo.com place the peak between November 2026 and January 2027, raising the prospect that much of the phenomenon’s effect on global temperatures will be felt in 2027 rather than this year.

A record set before the expected peak

The Niño 3.4 region covers part of the central tropical Pacific, and its anomaly measures the difference between sea-surface temperatures and a long-term reference average. In August, the monthly anomaly was about 2.45°C, exceeding the maximum recorded in most earlier events, although it remained below the 2015-16 peak of 2.75°C and the approximately 2.7°C reconstructed for 1877-78.

A separate index that accounts for broader warming across the tropical oceans reached about 2.5°C in mid-September, according to the same report. That was a record for that point in the year, though still below the daily record of 1982, which was set in late December.

Fourteen seasonal models and 674 simulations cited by Tiempo.com project a monthly maximum of about 4.1°C. Eighty percent of the simulations place the peak between 3.4°C and 4.6°C. The report cautions that seasonal forecasting systems have not previously been tested against an event of this scale and that August temperatures were about 0.3°C lower than the models had projected.

Unusual heat below the surface

Ivonne Montes, a researcher at Peru’s Instituto Geofísico del Perú, said the current ocean warming differs from the 2023 event. Data from Argo autonomous floats indicate that more of the heat is concentrated below 200 meters, whereas the 2023 warming was mainly near the surface.

“In this El Niño we are seeing warming below 200 meters, with a higher value than would have been expected,” Montes said, according to Diario Correo. The institute uses the floats to monitor ocean conditions in real time and improve forecasts for Peru’s coast. It deployed nine floats from 2021 and a further 15 in 2025.

Diario Correo reported that forecasts do not currently indicate major changes in rainfall in Peru’s Junín region. Montes said the available projections show rainfall at normal levels or slightly below normal, while stressing that El Niño’s effects vary across the country.

Potential consequences beyond the Pacific

El Niño changes atmospheric circulation over long distances and can affect temperatures, rainfall and storm activity in several regions. The available reports point to possible increases in drought, flooding, wildfires and abrupt temperature shifts, although the location and severity of impacts will depend on how the event develops.

The Climate Impact Lab projects about 451,000 additional heat-related deaths worldwide between June 2026 and February 2027. That estimate does not include possible deaths linked to droughts, wildfires and floods. It is a model projection rather than a confirmed toll.

BalkanWeb described surface anomalies above 4°C in some parts of the Pacific and cited subsurface anomalies approaching 10°C in areas of the upper 200 meters. Those figures are not corroborated by the other provided reports. The publication also cautioned that claims this could be the strongest El Niño in more than a century should be treated carefully because results vary according to the index and period used.

Scientists will continue to assess the event as new observations arrive. The record reached in September establishes an exceptional early benchmark, but it does not by itself determine the final intensity or the worldwide consequences of the 2026-27 El Niño.