Overview
- The National Energy System Operator issued an electricity margin notice warning the system could be 'squeezed' for the 7pm–10pm Wednesday peak but cancelled that notice in the afternoon after updated forecasts and market responses.
- Neso said the notice was a routine market tool to ask suppliers for extra capacity and stressed it did not mean the electricity supply was immediately at risk.
- Meteorologists forecast temperatures near 40°C in parts of England and Wales as a western-Europe 'heat-dome' raises household use of fans and air conditioning, which increases peak demand on the grid.
- Extreme heat and low wind reduce output and efficiency from thermal plants, cooling systems and wind generation, and rail operators including National Rail, Avanti West Coast, Chiltern and Eurostar have already cut or cancelled services for safety.
- The episode highlights how summer heat waves can strain multiple systems at once, and could raise the risk of further transport disruption or market notices if high temperatures and low renewable output persist.