Europe is experiencing an unprecedented heat wave, with temperatures reaching levels not seen since 1947. On June 23, France hit 44 degrees Celsius, pushing the power grid to its limits as millions turned on fans and air conditioners. Several power plants, especially nuclear ones, have been forced to reduce or halt production to avoid damage and comply with environmental regulations.
Golfech nuclear unit shuts down due to hot river water
On the evening of June 22, unit two of the Golfech nuclear plant in southern France was shut down around 11:45 PM. The reason is the temperature of the Garonne River, used for cooling. According to Brid Nelligan, a spokesperson for EDF, the move is precautionary. French regulations impose strict limits on the temperature of water returned to the river, and with water reaching 28 degrees Celsius, the operator had no choice. This event highlights the vulnerability of nuclear power to heat waves, a problem that has occurred before. In July 2025, at least seven gigawatts of nuclear capacity were forced offline for the same reason, more than the entire Irish grid.
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Other reactors reduce output
EDF, which operates France's entire nuclear fleet, has already reduced power at unit one of the Nogent-sur-Seine plant as of Tuesday, and further limitations are expected in the coming days. However, according to RTE, the national grid operator, these outages should not affect the ability to meet demand. The company stated the situation is under control, but the climate emergency requires significant investment to adapt infrastructure.
Impact on hydro and gas plants
Extreme heat does not only affect nuclear. Hydropower plants suffer from low water availability: in the first five months of 2025, European hydropower output dropped 13% year-on-year due to high temperatures and drought. Coal and gas plants also struggle: in the UK, five gas plants have reduced output by a total of about 2.5 gigawatts due to thermal stress. These figures are alarming and show how the entire energy system is exposed to climate change.
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Cooling demand doubles pressure on the grid
The main factor stressing the power grid is the surge in cooling demand, explains Jean-Paul Harreman, director of Montel. Even countries historically not reliant on air conditioning, like the UK, are adopting such systems: the number of British homes with air conditioning has roughly doubled since 2022. Globally, energy use for cooling is set to double by 2050 relative to 2023 levels, according to the International Energy Agency. Simone Tagliapietra, senior fellow at Bruegel, suggests utilities must adapt by planning for summer peaks, making cooling demand flexible, reinforcing grids, and climate-proofing plant cooling systems. Advanced data management frameworks, such as LlamaIndex, can help energy companies process large volumes of data to predict demand and optimize operations.
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Billion-dollar investments for climate resilience
The needed adaptations come at a high cost. EDF estimated that upgrading its nuclear and hydropower plants for resilience will cost about 600 million euros per year over the next 15 years. A significant expense, but necessary to ensure energy security in a changing climate. Heat waves like the current one, expected to continue throughout the week, are set to become more frequent and intense, as noted by authoritative sources like Wikipedia. The challenge is global, and Europe cannot afford to ignore it.
Source: https://www.technologyreview.com/2026/06/24/1139676/europe-heat-power-plants
