technology
Heatwaves Strain Power Grids, Rail Systems and Data Centres
Record temperatures in June 2026 caused transformer failures, hospital IT outages and rail equipment stress across parts of Europe and the UK. Engineers report efficiency losses in power stations, solar panels and transmission lines when temperatures exceed 27C. Infrastructure operators are adding cooling systems and expanding network capacity to handle more frequent heat events.
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A transformer in Ergué-Gabéric, Brittany, failed on 23 June when temperatures reached about 40C, cutting power to more than 100,000 customers. Local authorities classified the incident as heat-related. Power company RTE confirmed the equipment belonged to its network.
The same day, Paris closed the Eiffel Tower early. Six NHS trusts in England declared critical incidents after heat affected scanners, lab equipment and cancer-treatment systems.
Gas-fired power stations lose roughly 10% of output at 40C compared with 20C, according to Iain Staffell of Imperial College London. Solar panel efficiency also declines above 27C, though newer panels show smaller losses. UK solar generation data analysed by Staffell and colleagues show output plateaus and then falls once temperatures exceed that threshold.
Overhead power lines expand and sag in heat. Operators limit electricity flows on hot days to prevent contact with trees or buildings.
During the July 2022 UK heatwave, temperatures inside two London hospital data centres reached 36.2C and 50.3C after cooling systems failed, forcing cancellation of operations. Rail signalling cabinets can exceed 70C; Southeastern began testing liquid cooling in such cabinets last year.
Telecoms cabinets can also overheat. Operators have added ventilation or shielding at exposed sites. William Webb, chief executive of Commcisive, said widespread communications failures from heat remain unlikely. The independent Climate Change Committee warned in May that knock-on outages could cost billions.
