French evening power prices are nearing €300 per megawatt-hour as the country faces significant reductions in nuclear power output. This surge is primarily driven by a labor strike in the electricity sector, which took approximately 6.5 gigawatts of power offline overnight on Monday, September 14, 2026. The majority of these cuts, totaling several hundred megawatts, came from seven French nuclear reactors, alongside some gas-fired and hydroelectric plants.
The ongoing heatwave has further compounded the issue, leading to continued restrictions on nuclear plant operations. High river temperatures prevent plants from using water for cooling, forcing them to curb production to comply with environmental regulations. This has resulted in French nuclear output falling to its lowest levels in 15 months, with repeated curtailments throughout the summer of 2026. For example, a 7.3 gigawatt cut in output during the week of August 10, 2026, caused French day-ahead power prices to jump by 21.8% to €142.5 per megawatt-hour.
Adding to these challenges, Electricite de France SA (EDF) extended a maintenance outage at its Gravelines 5 reactor in northern France until January 25, seven weeks longer than initially planned. This prolonged shutdown, due to corrosion signs, will further reduce power output during the crucial winter heating season. These combined factors are putting upward pressure on European power prices, especially as gas prices are already high due to the Iran war.
