At present, a weak La Niña—the cooler-than-normal phase of ENSO—still persists in the equatorial Pacific. La Niña peaked in November and is expected to weaken further during the Northern Hemisphere winter.
More recently, however, ENSO temperature anomalies have begun to rise again, signalling that La Niña may be approaching its end.
Severe Weather Europe said the warming in the equatorial Pacific appears to be starting in the west, as shown clearly by sea-surface temperature anomaly data.
Signs of a possible El Niño are becoming even clearer below the ocean surface. Subsurface temperature anomalies show a large pool of warm water in the western Pacific at a depth of about 100–250 metres (300–800 feet).
Severe Weather Europe said this is one reason La Niña is weakening from the west, as these warm-water anomalies continue to expand beneath the surface.
Seasonal forecasts are also pointing towards a transition to El Niño. “The clearest signal of the upcoming El Niño can be seen in the latest seasonal forecast models for the ENSO region,” the platform said.
ECMWF projections indicate conditions will shift into El Niño during the summer of 2026 and extend into winter. For now, the event is assessed as moderate, though El Niño episodes often prove stronger than early forecasts suggest.
Current signals from sea-surface temperatures, subsurface ocean heat and forecast models resemble conditions observed ahead of the most recent El Niño in 2023–2024, a period associated with record-breaking monthly and annual global temperatures.
That episode was among the factors that made 2024 the hottest year on record and the first year in which the global average temperature rose above the 1.5°C threshold.