Heatwave expected to limit 15% of France's nuclear fleet on Friday

• Six French nuclear reactors expected fully offline Friday, with total curtailments reaching 9.4 gigawatts at peak - French day-ahead power prices rose 4.4% to €154.50 per megawatt hour, the highest since June 23
• France depends on nuclear for 70% of annual electricity production; environmental rules limit heat discharge into rivers, forcing output cuts when water temperatures rise during heatwaves with temps reaching 35-40°C
• Nuclear shortfall impacts neighboring countries including Britain and Germany, which must activate coal and gas plants to compensate for reduced French nuclear power exports

Summary: French Nuclear Output Curtailed 15% Due to Fifth Summer Heatwave

France's nuclear power production is expected to be reduced by approximately 15% of total fleet capacity on Friday, August 13, 2026, as the country faces its fifth heatwave this summer. Operator EDF data shows total nuclear curtailments will reach 9.4 gigawatts at peak, affecting nine reactors with six completely offline.

Market Impact:

The reduced nuclear output, combined with limited wind generation, has driven significant power price increases. French day-ahead contracts for Friday rose 4.4% to €154.50 ($178.08) per megawatt hour at 0756 GMT—the highest level since June 23. These elevated prices are particularly notable given August typically sees lower power costs due to reduced holiday-season demand.

Key Details:

• Peak temperatures expected to reach 35-40°C (95°F) on Thursday
• France depends on nuclear power for approximately 70% of annual electricity production
• Environmental regulations limit heat discharge into rivers, forcing output reductions during high water temperatures
• Relief expected Friday as cooler Atlantic air moves eastward

Cross-Border Effects:

The French nuclear shortfall is forcing neighboring countries, including Britain and Germany, to activate coal and gas plants to compensate for reduced nuclear power exports, highlighting Europe's energy interdependence.

Context:

Despite current outages, French nuclear production increased in June and July year-over-year as EDF optimized maintenance schedules. The Gravelines plant's reactors in northern France have recently returned to service. However, persistent heatwaves continue to challenge nuclear generation capacity across Europe, creating ongoing volatility in regional power markets.