Europe is in the middle of a record-breaking heat wave, and the grid is being pushed to its limits as people turn to fans and air-conditioning to try to stay cool. Some power plants won’t be online to help handle the load.

On June 23, France saw its hottest day since record-keeping began in 1947. Temperatures climbed to over 44 °C (111 °F), and overnight temperatures remained unusually high. This prolonged hot weather warmed up the water in some rivers across the country, a problem for the many nuclear plants that rely on those bodies of water for cooling. One reactor has already shut down, and others are being ramped down or will see limitations later in the week.

Unit two at the Golfech nuclear power plant in southern France shut down at about 11:45 p.m. on June 22 when the river used to cool the plant got too hot. The move was a precautionary measure, according to Brid Nelligan, a spokesperson for EDF, the plant’s owner and operator.

The power plant takes in water from the Garonne River and then returns most of it to the river at slightly higher temperatures after using it to cool equipment. French regulations limit the temperature of that return stream, so the warm water (it was expected to reach 28 °C, or around 82 °F) forced the operator to shut down the plant.

EDF, which operates France’s entire nuclear fleet, is also limiting the output of other reactors across the country—one reactor at the Nogent-sur-Seine power plant was ramped down as of Tuesday, and more will follow later in the week, Nelligan says.

Extreme heat has affected France’s nuclear industry before. At least seven gigawatts’ worth of nuclear energy was forced to shut down across the country during a heat wave in July 2025, according to data from Ember Energy. That’s more than the entire grid of Ireland. 

This time, power plant outages and limitations aren’t expected to be drastic enough to affect the ability to meet demand in France, according to RTE, operator of the national electric grid. 

Nuclear power has made most of the headlines during this heat wave, but other forms of electricity generation face similar challenges. Hydropower plants frequently run into problems when dry conditions lower the amount of water available to generate energy and force them to decrease or shut off operations. In the first five months of 2025, high temperatures and low water conditions cut hydropower supplies in Europe by 13% compared with the year before.

Even established coal and natural-gas plants can be challenged by high temperatures. Hot weather can stress equipment and limit the efficiency of cooling towers. Five gas plants across the UK have reported output reductions due to the conditions, cutting a total of about 2.5 gigawatts from the power supply. 

Increased demand, largely driven by cooling, is the main factor stressing Europe’s power grid, says Jean-Paul Harreman, director of Montel, an energy intelligence provider, via email. Even countries that haven’t historically relied much on cooling technologies are turning to them now—the number of UK homes that use air-conditioning has roughly doubled since 2022. 

Around the world, the challenges heat presents for the grid are only expected to get worse as climate change brings more frequent and intense heat waves. Globally, energy use for cooling is set to double by 2050 relative to 2023 levels, according to the International Energy Agency.

“Utilities can adapt by planning for summer peaks, making cooling demand more flexible, reinforcing grids for high temperatures, deploying batteries and demand response, and climate-proofing power plants’ cooling systems,” says Simone Tagliapietra, senior fellow at Bruegel, an economic and policy think tank, via email. 

But those changes could be expensive. Earlier this year, EDF shared a climate-change vulnerability assessment for its business, including nuclear and hydropower operations across France. Upgrades are expected to cost about €600 million per year (about $680 million) over the next 15 years. 

Meanwhile, high temperatures are expected to continue across much of Europe through the end of the week.