Europe's record heat forces nuclear plant shutdowns and grid strain

Europe is in the grip of a record-breaking heat wave, with France recording its hottest day since 1947 on June 23 (44°C/111°F). The extreme temperatures are not only driving surging demand for cooling—fans and air conditioners—but also forcing power plants offline. France’s state-owned utility EDF shut down Unit 2 at the Golfech nuclear plant in southern France on June 22 after the Garonne River, used for cooling, reached 28°C (82°F). French regulations cap the temperature of water returned to rivers, so the plant was proactively taken offline. EDF is also throttling output at the Nogent-sur-Seine plant and warned of further limitations later in the week. This isn't unprecedented: a July 2025 heat wave knocked out 7 GW of nuclear capacity—more than Ireland’s entire grid.

The heat wave isn't just hitting nuclear power. Hydropower generation across Europe fell 13% in the first five months of 2025 compared to the prior year due to low water levels and high temperatures. Fossil-fuel plants are also affected: five gas-fired units in the UK have reduced output by about 2.5 GW cumulatively. The primary stress on the grid is increased demand for cooling—UK air-conditioning adoption has roughly doubled since 2022. Climate change is expected to make such events more frequent and intense. EDF has released a vulnerability assessment projecting €600 million (≈$680 million) per year in adaptation costs over the next 15 years. Experts recommend utilities plan for summer peaks, deploy batteries and demand response, and climate-proof cooling systems.