French spot power forecast to top EUR 100 next week as heat threatens reactors again
Forecasters warn of another record-breaking heat episode centred on France, with river cooling constraints threatening nuclear output and regional supply balances.
Forecasters warned on 3 July (2026-07-03) of another "record-breaking" heatwave bearing down on France, naming the country's reactors as a direct market vulnerability and driving expectations that French day-ahead power will breach EUR 100 per megawatt-hour again for the week beginning 20 July (2026-07-20). German day-ahead power stood at €105.65 on Tuesday (2026-07-14), already elevated well before the episode arrives.6
France's nuclear fleet depends on river systems for cooling water, and environmental regulators impose thermal discharge limits that cap how much heat plant operators can return to waterways. When ambient temperatures stay high for several consecutive days, those limits force output reductions at riverside units. Montel reported that forecasters had specifically identified reactors as a market vulnerability for the coming period, with France named as the epicentre.6
The country operates more nuclear capacity than any other in Europe. Sustained curtailment at even a handful of riverside units can swing France from net exporter to net importer within days. Replacement supply must then flow through cross-border interconnectors from Germany, Belgium and Spain, all of which carry fixed physical limits. When temperatures run high across multiple countries at once, the margin on those links can disappear quickly.6
European power markets have been running at elevated levels on strong commodity costs, high carbon prices and low wind output, CNBC reported.4 Heat-driven reactor curtailments in France add direct upward pressure on that base, with each lost megawatt-hour of nuclear output requiring replacement at higher marginal cost.
With ICE Endex TTF front-month at €53.60 per megawatt-hour on Tuesday (2026-07-14), gas-fired generation is an expensive source of backup. Nuclear shortfalls met by open-cycle gas turbines push French day-ahead settlement sharply higher, and the spread between French and German contracts tends to widen when domestic French generation is under pressure.6
The longer-term supply picture adds a separate complication. The European Commission launched a formal investigation on 19 May (2026-05-19) into France's plan to subsidise the construction of six new reactors with a combined capacity of 10 gigawatts. The French government estimated the project at EUR 73 billion in 2020 euros, Montel reported.1
Negotiations between Paris and Brussels were still running as of 21 May (2026-05-21), with the French economy and energy ministry telling Montel the talks would continue for "the coming months."5 New capacity is years from commercial operation regardless of how those talks conclude, leaving the near-term supply picture entirely dependent on the existing fleet performing under worsening thermal conditions.
EDF OA, the division managing feed-in contracts for subsidised renewable assets, said it would curtail 842 megawatts of solar and onshore wind capacity during periods of negative spot prices.2 That measure protects the economics of legacy contracts. It adds nothing to available supply when heat-driven demand peaks and nuclear capacity is constrained — the part of the merit order that matters most in a heat event.
Germany's own power margin fell to its lowest seasonal level during the week of 18 May (2026-05-18), as low wind speeds strained its system, according to Bloomberg models cited by OilPrice.com.3 Cross-border capacity flows in both directions; a Germany operating under its own supply pressure has less room to absorb French import demand.
EDF's real-time reactor availability disclosures and the French-German day-ahead price spread will give the clearest reading on how far the regional grid is leaning on imports. River temperature conditions along the Loire and Rhône will determine whether environmental monitoring bodies issue operating directives to plant operators before the episode peaks.6