EDF Curtails 8.8 GW as French Nuclear Cuts Set Heatwave Record
Heat-related curtailments hit a record 9.2 GW on Sunday (2026-07-12), with 8.8 GW still offline Monday (2026-07-13) as temperatures hold and European power markets move higher.
France's heat-related nuclear curtailments hit a record 9.2 GW on Sunday (2026-07-12), Montel reported, as sustained high river temperatures pushed EDF to throttle output across multiple plants simultaneously. Swiss utility Axpo compounded regional supply pressure by again shutting down a reactor for the same reason.3
By Monday (2026-07-13) morning, EDF was still holding back 8.8 GW of French generation capacity, with temperatures forecast to remain elevated until around mid-week. The curtailment was equivalent to roughly 14% of France's total power demand as of Monday (2026-07-13) morning, according to OilPrice.com data — the deepest heat-driven output reduction the French system has recorded.3,4
French nuclear capacity ordinarily accounts for around 70% of the country's electricity mix, and when fully operational France is a consistent net exporter to its European neighbours. That exporter status gives heatwave-driven curtailments a reach beyond French borders. The country's spare megawatts routinely fill gaps across Germany, Switzerland, Spain and the UK when generation elsewhere tightens.4
German power futures reflected the squeeze. The German power contract was trading at €107.73 per megawatt-hour on Monday (2026-07-13), up 3.89% on the session. ICE Endex TTF front-month gas rose 1.45% to €51.78 per megawatt-hour, as markets weighed reduced nuclear availability against elevated cooling demand across the continent.3
Despite the curtailments, RTE data showed France remained a net exporter on Monday (2026-07-13), shipping more than 10 GW to neighbouring countries. That surplus persists largely because France entered the heatwave with most of its fleet operational, after several years of recovery from widespread maintenance shutdowns that paralysed exports earlier this decade. The headroom is meaningful. It also narrows with each additional gigawatt removed from service.4
Axpo's repeat reactor shutdown adds a Swiss dimension to what is principally a French supply event. Alpine rivers are running warm, and Axpo has now halted the same unit more than once during this episode, Montel reported — a pattern that signals persistent rather than transient thermal stress.3
EDF's reductions follow standard French thermal compliance rules, under which plants must cut output or halt when river temperatures breach regulatory thresholds protecting aquatic ecosystems. The thresholds are not discretionary; EDF cannot run through them regardless of the supply situation.3
MetDesk had flagged June as the period of greatest cooling risk for French reactors this summer, citing potential for low river levels and high water temperatures. The worst of the episode arrived in July instead. Montel cited forecasters in May who expected frequent summer thunderstorms to limit nuclear disruptions — a view that has not held through this stretch.2,1
EDF's 8.8 GW of curtailments on Monday (2026-07-13) sat just below the record 9.2 GW peak reached on Sunday (2026-07-12), suggesting conditions eased marginally overnight but the system is still operating near maximum thermal stress. If temperatures remain elevated into Wednesday (2026-07-15) or Thursday (2026-07-16), the record set on Sunday (2026-07-12) could be retested.3