El Niño 2026’s impact in wind: what 55 years of ERA5 data show
Written by Gerard Castro, Head of Technology at Nebbo.
In a recent post, we examined the El Niño 2026 forecast — the growing signal, the spring predictability barrier, and the case for acting early. That post focused on whether El Niño is coming and how strong it might be.This one addresses what comes next. If El Niño develops as expected, it will peak this winter — as ENSO events typically do between November and January. What does that mean for wind resource?
The short answer: El Niño shifts the probability distribution of wind outcomes across large parts of the world. In Europe, the signal shows up most clearly in the first half of winter. It is most relevant for operators exposed to Northwest European and offshore North Sea markets. However, it is not a guarantee of any particular outcome. The spread across historical El Niño winters is wide, and that spread is the most important thing to understand.
This post draws on a new analysis published by ECMWF’s C3S, authored by Christopher Goddard [1], who builds ERA5-based composites spanning 55 years to characterise ENSO’s global and European impacts.
El Niño’s reach: from Tropical Pacific to European pressure maps
When sea surface temperatures rise in the tropical Pacific, the resulting shift in atmospheric convection doesn’t stay local. It reorganises large-scale pressure systems across the Northern Hemisphere. These atmospheric bridges propagate the signal poleward, eventually leaving a fingerprint on the North Atlantic pressure field.
For European wind operators, that fingerprint is what matters. El Niño winters tend to drive a negative pressure anomaly over the central North Atlantic. This steers the jet stream, channelling westerlies more directly into the UK, the North Sea, Ireland, and Scandinavia. Other factors — including stratospheric variability and Arctic circulation — can, however, modulate or override this signal in any given year.
What ERA5 shows: the two halves of an European El Niño winter
Using ERA5 data from 1970 to 2025, Goddard [1] constructs mean sea-level pressure (MSLP) composites for El Niño winters. These are based on upper-quartile events of the relative Niño3.4 index, recently introduced by ECMWF and C3S [3]. The result reveals a practical structure that wind operators should keep in mind: early winter and late winter behave differently.
- November–December: El Niño composites show a strong negative MSLP anomaly over the North Atlantic. Positive anomalies appear to the south and east. This pattern is associated with enhanced westerlies over Northwest Europe — a wind-favourable signal for UK, Irish Sea, and North Sea markets. Moreover, the composite response is fairly coherent across historical El Niño events in this sub-period.
- January–February: the pattern evolves. The atmospheric response becomes structurally different from early winter, and the signal weakens. Molteni and Brookshaw (2023) [2] find the same early-to-late winter transition in ECMWF and C3S seasonal systems. They note that the two sub-periods require distinct treatment. Consequently, planning for the full November–February period as a uniform block will obscure the real structure of the risk.
Figure 1: ERA5 MSLP composites for El Niño events (upper quartile of DJF relative Niño3.4, 1970–2025), showing the mean circulation anomaly during early winter (Nov–Dec, left) and late winter (Jan–Feb, right). Anomalies relative to the 1991–2020 reference period. Extracted from Goddard [1].
In addition, Goddard’s analysis includes 10m windspeed anomaly charts — per-event postage stamps for each El Niño winter in the ERA5 record. These translate the MSLP composites into the variable that directly affects turbine output. They tell a consistent story: elevated wind speed anomalies appear over Northwest Europe in many El Niño ND periods. However, the event-to-event spread is immediately apparent.
The diversity problem
Composites are summaries. The most important message from Goddard’s postage stamp charts is therefore the diversity of individual outcomes. Seasonal forecast users sometimes lose sight of this.
Even the three strongest El Niño events on record — 1982/83, 1997/98, and 2015/16 — produced meaningfully different European wind patterns. In some years the composite signal is clearly visible; in others it is absent or reversed. The ENSO signal competes with other sources of variability, any of which can dominate in a given year. This is particularly true of the North Atlantic–European sector. There, influences from polar regions and the stratosphere play a significant role in both early and late winter [1].
Figure 2: 10m wind speed anomalies (percentage of the 1991–2020 reference-period mean) for El Niño winters identified by upper-quartile DJF relative Niño3.4 (ERA5, 1970–2025). Swipe left to see November–December maps; swipe right for January–February maps. The relative Niño3.4 index value is shown above each map. Extracted from Goddard [1].
Moreover, recent research adds a further caveat. The ENSO–North Atlantic-European teleconnection may be weakening as background SSTs and sea-ice conditions evolve under climate change [4]. The historical composite is therefore a guide to elevated probabilities, not a template to apply mechanically.
In practice, El Niño conditions raise the probability of wind-favourable westerly patterns over Northwest Europe in November and December. They do not guarantee them, and the late-winter picture is even less constrained.
The global picture
The wind signal from El Niño is not confined to the North Atlantic. Across the tropics and subtropics, El Niño’s trade wind weakening is a more direct, better-constrained effect. As a result, the wind energy implications are significant and in some cases well-quantified.
In Chile, for instance, important wind corridors sit within ENSO-sensitive trade wind regimes. Research has shown meaningful production-level impacts across ENSO cycles there [5]. Similarly, El Niño has historically suppressed wind resource in eastern Australia through weakened south-easterly trades. Furthermore, recent work on photovoltaic power documents sustained solar energy deficits across multiple global markets during El Niño events [6]. This is particularly relevant for operators managing mixed wind-solar portfolios.
What this means for wind operators and asset managers
If you manage a wind portfolio, the ENSO signal is worth integrating into seasonal resource planning — not as a deterministic forecast, but as a tool for probability-weighted scenarios.
Specifically, a few points stand out:
- P50 assumptions can drift during ENSO years: a strong El Niño shifts the distribution of November–December wind outcomes across Northwest European markets. Capacity factor projections built on climatological means will miss this.
- The two halves of winter are not the same: the early-winter signal (Nov–Dec) is more coherent and actionable; in contrast, the late-winter signal (Jan–Feb) is weaker and more uncertain. Month-by-month scenario planning is therefore more robust than a single seasonal average.
- North Sea and UK offshore wind are particularly sensitive to NAO-like pressure patterns, which El Niño tends to favour in early winter. Assets in these markets carry the most direct exposure.
- Correlated portfolio exposure: an ENSO-conditioned wind year can create systematic biases across geographically correlated assets. An asset-level view may not capture this.
Acting on the signal
The seasonal forecast tools to act on this exist and are improving. ECMWF’s SEAS5 system and the C3S multi-model ensemble both incorporate ENSO state in their forecasts. As a result, their probability distributions will increasingly reflect the developing El Niño signal as winter 2026/27 approaches. The right move is therefore to use them now to frame scenarios — and to narrow those scenarios as subseasonal forecasts sharpen through autumn.
As argued in the previous post: build contingency scenarios now, not after certainty arrives. That principle applies as much to resource planning as to event forecasting.
At Nebbo, this is the kind of intelligence we provide — translating ENSO signals and seasonal outlooks into actionable insights for energy companies, traders, and asset managers. If you are thinking about how the evolving forecast picture might affect your operations or portfolio, we would be glad to talk.
References
[1] Christopher Goddard, ECMWF/C3S — ENSO impacts (based on ERA5 reanalysis) (2026)
[2] Molteni, F. and Brookshaw, A., Early- and late-winter ENSO teleconnections to the Euro-Atlantic region in state-of-the-art seasonal forecasting systems. Clim Dyn 61, 2673–2692 (2023). https://doi.org/10.1007/s00382-023-06698-7
[3] Stockdale, T., Measuring the strength of El Niño — introducing Relative Niño indices, ECMWF Science blog post (2026). https://doi.org/10.21957/d05ccfe150
[4] Beverley, J.D. et al., Drivers of Changes to the ENSO–Europe Teleconnection Under Future Warming. Geophys. Res. Lett. 51 (2024). https://doi.org/10.1029/2023GL107957
[5] de Jong, P. et al., How does El Niño Southern Oscillation impact the wind resource in Chile? Renewable Energy 96 (2016). https://www.sciencedirect.com/science/article/abs/pii/S0960148116308977
[6] Photovoltaic power response to El Niño–Southern Oscillation. Commun. Earth Environ. (2026). https://doi.org/10.1038/s43247-026-03343-z
[7] Hersbach, H. et al., The ERA5 global reanalysis. Q J R Meteorol Soc. 146: 1999–2049 (2020). https://doi.org/10.1002/qj.3803
