The National Energy System Operator (Neso) has called for increased electricity generation as the UK experiences its third heatwave of the year, with temperatures set to reach 36C and air-conditioning usage surging. The operator issued an electricity margin notice forecasting tight supply margins due to extreme temperatures across Europe, which reduce the efficiency of power generation from nuclear plants, gas stations, and water cooling systems.
Third Margin Notice of the Year
This is the third such notice from Neso in 2026, typically issued during winter cold snaps when heating demand spikes. However, extreme heat also strains the grid by lowering generation efficiency and increasing demand for fans and air conditioning. The notice signals to the market that Neso seeks a greater safety cushion between supply and demand for a limited period, though it does not indicate imminent blackouts or insufficient generation.
On Wednesday evening, a Neso spokesman said: “Our forecasts indicate tight electricity margins during tomorrow evening’s peak period. This is due to extreme temperatures across Europe, reducing the availability of some generation.” The body confirmed it would continue monitoring conditions and take necessary actions to maintain secure supplies.
Previous Callouts Cancelled
Neso, tasked with balancing national electricity supply and demand, issued similar callouts twice in June. Both were cancelled ahead of time, indicating confidence in supply levels. The current notice comes amid health and fire warnings as temperatures soar, with the Met Office forecasting that heat will peak Thursday and Friday, widely exceeding 30°C across the UK and hitting 36°C in parts of England.
Impact of Extreme Heat on Infrastructure
Extreme heat reduces the efficiency of thermal power plants, including nuclear and gas-fired stations, as well as water cooling systems. This, combined with increased electricity use for cooling, creates a tight margin situation. Neso's notice aims to prompt additional generation to ensure grid stability during peak demand periods.
