Winter 2026/27

Winter 2026–2027 outlook for Northwest Europe (including the UK): Mild and wet baseline with elevated storm risk, plus scope for colder interludes later.

This forecast is based on the dominant teleconnections (primarily a historic-strength El Niño), supporting signals from seasonal models (ECMWF SEAS5 and multi-model Copernicus/C3S ensembles, with supporting context from systems analogous to GFS/CFS and ICON-style guidance), polar vortex/stratospheric signals, and historical analogues of strong El Niño winters. Confidence is moderate for the large-scale pattern (milder/wetter tendency) and lower for precise timing of cold snaps or individual storm sequences. Seasonal forecasts are probabilistic; individual months can deviate substantially.

Primary Driver: Super/Historic El Niño. 

 As of early November 2026, a very strong to potentially record El Niño is underway and still intensifying. Niño 3.4 anomalies have recently reached the +2.5 to +3.4°C range (with higher values farther east), and multi-model guidance (including NOAA CPC, IRI, WMO, and ECMWF) points to a peak around late 2026/early 2027, with values potentially exceeding +3°C to ~+3.7°C or higher in some ensembles. Odds of a historic event (stronger than any since at least 1950 on key metrics) are high for OND 2026 (~83% in some CPC assessments), with strong-to-very-strong conditions likely persisting through JFM 2027.​

 Strong El Niño typically strengthens and shifts the North Atlantic jet stream southward. This favors more frequent and intense Atlantic storms tracking toward the UK and Northwest Europe, milder overall temperatures (especially early–mid winter), and above-average precipitation. Historical strong events (e.g., 1997–98, 2015–16) produced notably stormy, wet, and relatively mild UK winters with flooding risk. The influence is stronger on the large-scale circulation than on local details.

 Supporting Teleconnections and Stratosphere.

Polar vortex / AO / potential SSW: Early signs of disruption or stretching appear in November 2026 guidance (some sources note possible early weakening or sudden stratospheric warming elements). El Niño can favor wave activity that weakens the vortex later in winter. A weaker vortex raises the odds of negative AO phases and Arctic/cold air outbreaks into mid-latitudes (including Europe) on a 2–6 week lag. This is a key wild card for mid-to-late winter cold potential.
NAO: ECMWF SEAS5 (November initialization) shows a preference for negative NAO through much of winter, with the strongest median signal around February. Negative NAO favors higher pressure near Greenland/Iceland, a more blocked or meridional pattern, and greater potential for colder outbreaks into the UK/Northwest Europe (especially if combined with polar vortex disruption). Spread remains large.​

QBO: Reports indicate a westerly phase, which typically supports a more stable polar vortex and can partially counteract El Niño’s disruptive influence. This adds uncertainty.
Other factors (e.g., North Atlantic SST patterns, including any persistent cool anomalies in the subpolar gyre) can modulate the jet and storm track but are secondary to the El Niño signal at this stage.

Seasonal Model Guidance (ECMWF SEAS5 / Copernicus Multi-Model Focus) 

Latest available runs (October–early November 2026 initializations) show broad agreement on the following for DJF 2026–27 over Northwest Europe/UK:
Temperature: Above-normal tendency across most of Europe. British Isles signal is typically modest (around +0.5 to +0.8°C relative to model climatology in many SEAS5 depictions), with stronger warm anomalies farther south and east. High probability of warmer-than-average overall, but cold members exist in the ensemble (spread can be several degrees). The mild signal is partly amplified by the background warming trend.

Precipitation: Wetter signal favored over western and central Europe, including the UK and Ireland (roughly +8–9 mm/month anomalies in some SEAS5 views for the British Isles/France region). Agreement among members is moderate (~50–70%). This aligns with the strengthened Atlantic storm track. Flood risk is elevated, especially on already-saturated ground in successive storm events.

Pressure/Circulation: Tendency for lower pressure over the North Atlantic extending toward northern Europe, consistent with active westerlies early on, transitioning toward more blocked/higher-latitude pressure signals later (supporting the negative NAO preference).
Multi-model means (Copernicus) reinforce the mild and relatively wet picture for large parts of Europe, with the weakest warm signal often over Scandinavia. Snowfall at low elevations is expected to be below average due to the milder air and higher snow line; better prospects mainly at higher elevations or during any colder outbreaks.
Analogous guidance from other systems (CFS-type, etc.) generally supports the El Niño-driven stormier/milder theme for the UK sector, though details vary run-to-run. 

 Expected Character by Period (Probabilistic).

 Late autumn / early winter (Nov–Dec / early Jan): Highest confidence in the classic strong-El Niño signature — active Atlantic jet, frequent mild/wet/stormy spells for the UK and Northwest Europe. Named storms and periods of heavy rain/flood risk more likely than average. Temperatures mostly above or near normal, with limited sustained cold.
Mid-to-late winter (Jan–Feb, especially later): Greater uncertainty and potential for variability. Polar vortex disruption + negative NAO preference open the door to colder, more blocked spells with possible snow (particularly if cold air is drawn from the north/east and meets residual moisture). These are more likely as short-to-medium duration events rather than a prolonged freeze. Overall seasonal mean still leans mild.

 Snow prospects (UK lowlands): Below average in the baseline mild/wet regime. Meaningful accumulations more plausible during any late-winter cold outbreaks. Highlands and higher ground have better chances relative to lowlands.

 Key Uncertainties and Caveats.
Seasonal skill over the North Atlantic/Europe is moderate at best, especially beyond the first 1–2 months. The extreme strength of this El Niño is outside much of the historical training data for models, so analogues and ensemble spread matter more than the mean. Stratospheric coupling is inherently uncertain in timing and downward impact. Internal variability (MJO, individual blocking events) can override the seasonal signal for weeks at a time.
Bottom line: The most likely outcome is a milder-than-average, wetter-than-average winter for the UK and Northwest Europe, driven by strong El Niño forcing of the Atlantic jet and storm track, with elevated flood/storm risk. There is a realistic secondary scenario of more variable conditions later, including colder/snowier interludes if the polar vortex weakens and negative NAO develops as preferred in some SEAS5 guidance. Monitor updates to stratospheric forecasts, NAO evolution, and the next round of seasonal model runs (especially after the peak El Niño signal clarifies further).

Cheers 

David.