Across the tropical Pacific and Indian Oceans this summer, two separate temperature anomalies are intensifying at the same time — and forecasters are paying close attention to what that combination could mean.
A rapidly strengthening Super El Niño is already generating subsurface ocean temperatures more than 8 degrees above normal in parts of the Pacific. Meanwhile, an emerging pattern in the Indian Ocean — known as the positive Indian Ocean Dipole — is quietly amplifying alongside it. Each event reshapes global weather on its own. Together, this kind of dual-ocean setup is rare.
NOAA and leading seasonal forecast centers are now tracking how these two systems may operate as a single, connected atmospheric engine heading into Winter 2026/2027.
A rare dual-ocean setup takes shape
The Indian Ocean Dipole doesn’t get as much attention as El Niño, but it carries real weight. The IOD works by creating opposing temperature anomalies across the Indian Ocean: warmer water in the west, cooler water in the east. During a positive phase, air rises over the warm western side and sinks over the cooler eastern region, generating a large atmospheric circulation cell that extends well beyond the Indian Ocean basin.
What connects the IOD to El Niño is the same machinery driving both: trade winds, tropical convection, and atmospheric pressure shifts. Weaker trade winds across the Indian Ocean promote warmer western waters, while stronger winds in the east drive the cooling that defines the positive phase. Those wind pattern changes tie directly to the pressure shifts already underway from the developing Super El Niño in the Pacific.
The last comparable positive IOD fall phase occurred during the 2023/2024 El Niño event. What makes the current setup notable is that seasonal forecasts now show this positive IOD persisting through fall and into early winter — not a brief spike, but a sustained event with enough duration to meaningfully influence global circulation patterns.
Super El Niño: What the bubsurface data reveals
The surface picture alone is striking. Peak anomalies in the central and eastern Pacific are already reaching +7.2 to +9°F above normal — and we’re only in early August, months before this event is expected to peak. The Super El Niño threshold sits at +3.6°F. Current readings are already well past that, according to the Australian Bureau of Meteorology.
The more telling signal, though, is underground. Subsurface temperature data shows a warm anomaly exceeding +14.4°F in the top 500 meters of the tropical Pacific — a structure known as a Kelvin Wave. Driven by strong tropical westerly winds, this mass of warm water is moving eastward and rising toward the surface, where it’ll keep fueling the event through peak season.
Both the ECMWF seasonal forecast and the NCEP CFSv2 model show this event surpassing the +5.4°F threshold — a level that would make it one of the strongest El Niño events in recorded history. The ECMWF’s most recent forecast, its strongest yet, shows peak anomalies exceeding +10.8°F in the broader ocean view. The atmospheric footprint is already visible: persistent rising air sits over the tropical Pacific while sinking air dominates the Indian Ocean, effectively locking the circulation in place.
How two oceans drive one global weather engine
When El Niño and a positive IOD operate simultaneously, they don’t simply add their effects — they synchronize them. Rising air over both the central Pacific and the western Indian Ocean launches coordinated atmospheric wave trains that travel poleward, directly reshaping the jet stream across North America and beyond.
Research published in 2025 helps explain the mechanism. Raganato et al. (2025) examined the combined link between the IOD and ENSO and their influence on North Atlantic–European circulation during early boreal winter, using both reanalysis data and ECMWF seasonal model hindcasts. Thomas and Bala (2025) separately documented robust tropical circulation changes under a warming climate. These studies underpin the teleconnection patterns forecasters are now applying to the 2026/2027 outlook.
One consistent finding stands out: real-world winter storms feed on this combined tropical energy more aggressively than models typically predict. Actual jet stream shifts tend to lock in faster than model output suggests.
The resulting pressure wave train is now appearing in ECMWF forecasts. A deep low over the North Pacific forces a strong ridge over Canada, which drives another low-pressure zone across the southern United States and into the North Atlantic — a repeating chain of pressure systems acting as a planetary-scale atmospheric highway, with direct consequences for both North America and Europe.
North America: A continent split in two
The ECMWF December pressure forecast is already showing a high-amplitude pattern across North America. A large blocking high sits over Canada while a deep, energetic low-pressure zone sweeps from the North Pacific across the southern and eastern United States. This is a textbook Super El Niño configuration.
The temperature consequences follow directly from that pressure layout. Canada, the northern and western United States, and the Northeast are forecast to see above-normal warmth. Texas, the Gulf Coast, and the Southeast sit under the southern low-pressure track — bringing cooler-than-normal temperatures driven by persistent cloud cover, rain, and an active storm track rather than Arctic outbreaks alone.
The snowfall picture shifts southward as a result. Higher snow potential is forecast for the Central Plains, parts of the Midwest, the Mid-Atlantic, and the Southeast, where Pacific moisture can interact with periodic cold air drops from Canada. The Pacific Northwest and northern Great Lakes face below-average snowfall as the northern ridge keeps polar air displaced.
This pattern isn’t expected to relax as winter deepens. ECMWF’s February forecast shows the pressure wave intensifying further, locking the continent into an even more amplified configuration. Where heavy Pacific moisture meets cold air along the southern storm track, the risk of major winter storms and ice events rises considerably.
Europe: Mild, Wet, and Occasionally Disrupted
Europe sits downstream from the North American pressure pattern, and the connection is direct. As the atmospheric wave train crosses North America, it pushes low-pressure anomalies into the North Atlantic, strengthening the westerly flow into the European continent. The result is a winter shaped primarily by mild Atlantic air rather than polar intrusions.
ECMWF forecasts above-normal temperatures across most of Europe for December through February. The dominant westerly flow keeps cold air largely at bay, though the pattern isn’t uniformly mild — individual low-pressure systems moving inland can still deliver northerly intrusions. The UK and Ireland are most exposed to periodic cold disruptions as those systems track northeast.
That same westerly flow also brings moisture. Above-normal precipitation is expected across the continent through the core winter months, though broad snowfall remains limited under this pattern. Meaningful snow potential is largely confined to northern and northeastern Europe and higher-elevation areas, where cold air can still establish itself during brief northerly episodes.
What to watch as the season approaches
The dual-ocean setup described here is still evolving. The positive IOD is just entering its active phase, and the Super El Niño hasn’t yet reached its peak. Forecasts will sharpen considerably as updated model runs arrive through August and into fall.
Four signals are worth tracking closely: the persistence of the positive IOD through October and November, the rate at which the subsurface Kelvin Wave continues rising to the surface, whether the atmospheric standing wave over the tropical Pacific maintains its current strength, and how consistently the southern storm track can tap into cold air from Canada. If the first three hold, the winter forecast framework outlined here becomes increasingly credible.
For North America, cold air supply is the critical variable. The southern storm track can deliver moisture and energy, but major ice events and heavy snow require a reliable source of cold air from Canada. How often that cold air breaks southward will ultimately determine how disruptive the season becomes. Dedicated regional forecasts for the United States, Canada, and Europe are expected once August model data is refreshed — and those updates will offer a clearer picture of just how far this dual-ocean engine can reach.
Read the whole thing?
Get the week's signal, not the noise
Our sharpest reporting on energy, climate and nature — free, once a week.
