Rapid Super El Niño Formation in Pacific Expected to Impact European Weather This Autumn

A powerful El Niño event is forming at an accelerated rate in the Pacific Ocean, with scientists predicting it will significantly affect weather in Europe and North America this autumn and winter. Sea surface temperature anomalies in the eastern Pacific have already reached 3–4°C above normal, an unusually rapid onset. For the event to be classified as a "Super El Niño," seasonal indices must exceed +2°C, and current forecasts indicate this threshold will be easily surpassed, possibly reaching +3°C. If these projections hold, it would be the strongest El Niño in recorded history.

The initial impacts are expected in North America and tropical regions, later spreading globally. Analysis of past strong El Niño events suggests higher temperatures in the northern and central United States, southern and western Canada, and Western Europe. Conversely, temperatures may remain near or below normal in the U.S. West Coast, Southeast, northern Canada, and Central Europe. Precipitation is forecast to increase in the central and southern U.S., extending across the Atlantic to southern Europe, while deficits are expected in the northern and northeastern U.S. and central and northwestern Europe.

Weather models, including the European ECMWF and North American NMME, show atmospheric pressure patterns more typical of mid-winter than autumn. A high-pressure zone is forming over Canada, with active cyclones over the southern U.S. In Europe, low pressure over the Atlantic could bring wetter and more variable weather to the UK and Ireland. By January, this pattern is expected to intensify, with a stable high-pressure area over Canada and Greenland potentially directing cold air southward into the central and eastern U.S., while moist air flows from the south. This increases the likelihood of strong winter storms and sharp temperature contrasts.

A key factor is the polar vortex. In January 2026, the vortex already experienced a significant disturbance due to a stratospheric pressure anomaly, causing cold air outbreaks into the U.S., Canada, and parts of Europe. A strong El Niño raises the probability of similar stratospheric warming events, which would weaken the vortex and allow polar cold to spill into mid-latitudes. Forecasters advise close monitoring of the polar vortex, as it will determine the severity of winter.

Interestingly, while El Niño strengthens in the Pacific, a rarer cold period—an Atlantic La Niña—has been observed in the Atlantic Ocean. Although these phenomena have opposite temperature effects and occur in different oceans, together they may create an "atmospheric shield" that hampers hurricane formation. According to NOAA, the probability that El Niño will persist through spring 2027 is 97%, and the chance of a very strong event from October to December is 81%.