Stormy winter El Niño warning for the UK’s power grid
Key Points
- The Met Office said this El Niño is the strongest on record
- It raises the chance of a stormier UK autumn and early winter
- NESO expects a 5.5GW electricity surplus this winter
- January is the most likely period for tight supply days
- NESO publishes its full Winter Outlook in October
A record-breaking El Niño has raised the risk of a stormy UK winter and added pressure on the power grid.
The Met Office said the El Niño in the Pacific Ocean has become the strongest event in the observational record, with sea-surface temperatures in the central equatorial Pacific now above those of any previous event.
The forecaster warned of an increased chance of wetter and stormier conditions across north-west Europe, including the UK, during autumn and early winter. It also linked El Niño to a higher risk of cold snaps later in the season.
“We have been signalling for months that the developing El Niño will be an unprecedented event,” said Adam Scaife, Head of long-range prediction at the Met Office.
The Met Office expects the event to keep building towards its seasonal peak later this year.
The National Energy System Operator (NESO), which runs Great Britain’s electricity system, said it expects a surplus of 5.5GW between 31 October 2026 and 31 March 2027, with an 8.8% buffer over expected peak demand.
NESO measures this margin as the expected spare capacity during peak demand in an average cold spell, after meeting its reserve requirements.
That margin sits below last winter’s forecast, when NESO predicted 6.1GW, the highest margin since 2019/20.
NESO said some periods may be more finely balanced, particularly in January, but it has operational tools to manage tighter days and keep the system secure.
It expects Great Britain to be a net importer of electricity over the winter, with prices at a premium compared to France.
NESO forecasts a small increase in demand this winter, which it expects new generation and storage capacity to offset.
The grid operator has warned before that its forecasts can slip. Its review of last winter found that actual available conventional generation came in below forecast for much of the period, due to extended and new generator outages.
NESO based its assessment on modelling of around 30,000 scenarios and said it will keep monitoring global gas markets, European electricity flows and weather conditions. Its full Winter Outlook report is due in October.
