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Heatwave expected to remove 15% of France's nuclear capacity on Friday - Finance news and analysis from Global Banking & Finance Review
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Heatwave expected to remove 15% of France's nuclear capacity on Friday

Published by Global Banking & Finance Review

Posted on August 13, 2026

3 min read

· Last updated: August 13, 2026

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France to Cut 15% of Nuclear Power Capacity Friday Due to Heatwave

Impact of Heatwave on French Nuclear Power Production

By Forrest Crellin

Heatwave Effects on Nuclear Output

PARIS, Aug 13 (Reuters) - Europe's fifth heatwave this summer is expected to trim French nuclear power production by about 15% of the nuclear fleet's total capacity on Friday, with six reactors expected to be fully offline, data from operator EDF showed.

Temperatures in Europe have risen to unprecedented levels after successive heatwaves this summer, causing water shortages, wildfires, and some deaths.

Nuclear Curtailments and Outages

Total nuclear curtailments are expected to reach 9.4 gigawatts at the peak on Friday across nine reactors, EDF data showed.

The heat-related outages combined with the regular maintenance schedule, technical issues and fuel saving are expected to put some 27.7 GW of nuclear power offline on Friday, the lowest level of nuclear availability since August 2023, data from LSEG Power Research showed.

Effect on Power Prices and Exports

Low nuclear production paired with limited wind output lifted power prices, with the French day-ahead contract for Friday the highest since June 23, the previous peak this summer, up 4.4% at €154.50 ($178.08) per megawatt hour, LSEG data showed.

Power prices are traditionally much lower in August as it is a major holiday month in France, limiting demand.

The nuclear shortfall also ripples across borders, forcing countries such as Britain and Germany to turn on coal and gas plants to replace reduced exported nuclear power.

Even with the low nuclear availability, France continues to be a net exporter of electricity but is sending less power than average, LSEG analyst Nathalie Gerl said.

Average scheduled net exports for August have fallen to around 9.5 GW, approximately 20% lower than in July, which means European neighbours are still receiving a quite substantial power flow from France and the reliance on French export stability is high, she said.

Environmental Regulations and Weather Forecast

France relies on nuclear power for about 70% of its annual electricity production. French rules limit how much heat plants can discharge into rivers for environmental protection, forcing reactors to cut output when water temperatures rise during heatwaves.

Thursday is expected to be the peak of the current heatwave, with temperatures between 35 degrees Celsius (95 degrees Fahrenheit) and 40 C in most regions of the country, Meteo-France said.

Temperatures are expected to stay warm overnight, with some cooler air coming from the west and bringing relief on Friday to areas along the Atlantic and English Channel first, while the rest of the country remains warm, Meteo-France said.

Outlook for Nuclear Production

Despite the continued outages, nuclear power production in France increased in June and July compared to the previous year as EDF has reworked its nuclear fleet maintenance schedule.

Two of the jellyfish-hit nuclear reactors at the Gravelines plant in the north of the country are expected to remain offline for several more days.

(1 = 0.8676 euros)

(Reporting by Forrest Crellin; Editing by Sharon Singleton and Keith Weir)

Key Takeaways

  • Heatwave-driven river-temperature limits will reduce nuclear output by ~9.4 GW across nine reactors, amounting to ~15% of capacity (EDF data).
  • Total nuclear outages, including maintenance and other disruptions, will reach ~27.7 GW — the lowest availability since August 2023 (LSEG Power Research).
  • Higher power prices (day-ahead €154.50/MWh) result from low nuclear supply and weak wind; France remains a net exporter but with ~20% lower August exports than July.
  • The nuclear constraints ripple internationally—Britain and Germany may ramp up coal and gas to compensate for reduced French exports.
  • River-cooling restrictions are recurring: similar heat events in June forced curtailments at plants using Rhône, Garonne and Seine water, slashing export margins (WSP, Kpler).

Frequently Asked Questions

How much French nuclear capacity will be offline due to the heatwave?
About 15% of France's nuclear capacity is expected to be offline, with six reactors fully shut down.
How do heatwaves affect French nuclear power plants?
Heatwaves raise river water temperatures, forcing reactors to cut output to meet environmental regulations on heat discharge.
How does reduced nuclear output impact power prices in France?
Low nuclear production and limited wind power have pushed French day-ahead power prices to their highest since June.
Does France remain a net electricity exporter during low nuclear availability?
Yes, France still exports electricity, but at lower levels, with scheduled exports down 20% from July.
What other effects has the heatwave had on France’s energy system?
It caused some reactors impacted by jellyfish to stay offline and led to increased reliance on coal and gas plants in neighboring countries.

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