Repeated record-breaking heat waves cooked the European continent this summer, delivering the region’s hottest June on record. A simultaneous, though possibly related, drought shriveled rivers to record lows. In addition to their impact on public health, the dual crises put pressure on Europe’s energy system: Wind power struggled under stagnant conditions created by heat waves, and “thermal” power plants — nuclear, gas, and coal plants — had to reduce their output as European waterways warmed and dried, taking away water used for their cooling systems.
Solar power proved the only major energy source that performed better than normal during Europe’s summer of extremes, experts found. When paired with batteries, it helped supply thousands of AC units during historic hot conditions.
Scientists are still trying to understand why so many recurring heat waves materialized this summer, but studies have found that individual heat events are more likely and more intense because of climate change. The intensity of the June heat wave that scorched Western Europe was roughly 200 times more likely in today’s fossil fuel-warmed climate than it would have been two decades ago, one study found. As the continent continues to warm and Europeans install more cooling systems to cope — just 23 percent of households currently have access to or use air conditioning — experts say this summer provides lessons for the future.
Extreme temperatures in late June bumped up Italy’s power demand by 28 percent compared to the previous week, according to the energy think tank Ember. In France, that number was 14 percent. Electricity and natural gas prices spiked in evening hours as demand grew highest and solar generation ended, with some prices hitting their highest levels since the 2022/2023 winter gas crisis following Russia’s invasion of Ukraine.
As demand and prices were climbing, power generation in some areas was falling. In the United Kingdom, five gas plants reduced their output by a combined 2.5 gigawatts in generation because heat reduced their cooling systems’ effectiveness. At the same time, heat-induced low wind speeds halved the country’s typical wind farm generation in June.
Historic dryness dropped river levels across Europe: England and Wales reported their driest July on record, while water levels in the Danube River in central and Eastern Europe reached record lows, exposing WWII shipwrecks and prehistoric relics. Europe’s hydropower production hit its lowest July level in a decade, and multiple countries curtailed nuclear power generation as warm, low rivers threatened water supplies for cooling. France lost 18 percent of its nuclear capacity to “environmental factors” in mid-July, Ember found, extending a trend of summertime nuclear outages that has plagued the country in recent years. French nuclear plants often use river water as a vital component of their cooling systems, drawing the water in at natural temperatures and then discharging it back into the rivers slightly warmer. Because French law caps the temperature of this discharged water to protect aquatic life, plants must reduce cooling operations and related power generation when the intake water from rivers is already warm because of heat waves or drought.
But where these sources faltered, solar shone through. European heat waves tend to deliver optimal conditions for solar power: clear, sunny days. Europe’s solar panels produced 17 percent more power during the summer’s heat waves than they normally do, stabilizing the grid as afternoon cooling demand climbed, according to Ember. Battery systems helped deliver this solar power into the evening hours, when heat still lingered and air conditioners cranked to allow households to sleep.
“The next challenge is the evening period. Temperatures often remain high after sunset and AC demand can stay elevated, even as solar production declines,” said Walburga Hemetsberger, CEO of SolarPower Europe, an industry group. “This is why battery storage is becoming such an important part of the energy transition.”
For as much as this summer’s extreme heat strained Europe’s grid, the continent’s cooling demand has a lot of room to grow: About half of households in Italy and Spain have air conditioning, and a quarter in France — compared to 90 percent in the United States.
“There are places where we just can’t do without it now,” Marine Tondelier, national secretary of the Ecologist Party, said this June, a reversal in the party’s longstanding argument against air conditioning because of its greenhouse gas emissions.
France’s state-owned utility plans to spend over $10 billion to adapt its nuclear and hydropower plants to warmer temperatures and lower water availability over the next 15 years, including investments in equipment that cools the water nuclear plants discharge into rivers so that it complies with environmental standards. But adapting to that new demand could also take new generation and storage, especially as grids simultaneously increase demand from data centers.
Solar and batteries have already been growing at a breakneck pace across Europe, with 36 gigawatt-hours installed in 2025, a 48 percent increase over new additions the previous year. Battery installations saw their 12th straight year of growth in 2025, according to industry group SolarPower Europe.
“Extreme price spikes during heatwaves are a blaring signal for regulatory changes that increase power system flexibility,” said Beatrice Petrovich, a senior energy analyst covering Europe at Ember. “Treating this summer as a turning point for energy storage would be an opportunity to remove existing barriers.”