French Winter Cold and Its Impact on European Power Markets
Temperature drops in France trigger significant shifts in regional electricity exports and prices.
1Temperature and Export Correlation
French winter temperatures directly dictate regional power flows. Every single degree Celsius drop in French effective temperature reduces net exports by approximately 1 GW. This phenomenon impacts neighboring grids in Belgium, Germany, Switzerland, Britain, Spain, and Italy, which must compensate for the sudden loss of French supply during cold spells.
2The 2025/26 Winter Mechanism
The winter of 2025/26 illustrated this mechanism clearly. During a mild period in December, France exported 16.3 GW, but as temperatures plummeted to 1.9 C in late December, exports dropped to 5.7 GW. By January 6, with temperatures at -1.5 C, France became a net importer of 3.7 GW of electricity.
3Demand-Driven Export Volatility
The swing in exports is primarily driven by rising domestic demand rather than supply failures. French demand increases by 1.8 GW for every degree colder. While nuclear output provides some stability, it cannot fully offset the surge in demand, forcing France to reduce exports to maintain its own grid balance.
4Impact on Neighboring Countries
When France experiences cold, the impact is felt across borders. Belgium loses 0.28 GW per degree, Germany 0.26 GW, and Switzerland 0.21 GW. These figures represent the French temperature effect alone, excluding the simultaneous cold weather in neighboring countries, which further complicates the regional power supply and increases cross-border grid stress.
5Nuclear Fleet as Deciding Factor
The ability of France to maintain exports depends heavily on the performance of its nuclear fleet. In January 2025, with 55 GW of nuclear output, France exported 7.2 GW during a cold spell. Conversely, in December 2022, with only 40 GW of nuclear output, the country was forced to import 8.0 GW.
6Solar Energy's Limited Role
French solar output remains largely unaffected by temperature, as winter production is dictated by the calendar and short daylight hours. Even with quadrupled capacity since 2015, solar covers only 2.6% of demand on the coldest days. Doubling solar capacity would only marginally address the 23 GW demand gap between mild and cold days.
7Price Formation During Cold
Cold weather significantly inflates electricity prices. On the coldest tenth of winter days, French day-ahead prices averaged 113 EUR/MWh, compared to 61 EUR/MWh on mild days. This price spike ripples across Europe, with the French premium over Germany flipping from a negative value on mild days to 12 EUR/MWh during cold spells.
8Solar Capture Rate Dynamics
Solar capture rates actually rise during cold spells because midday price suppression from solar generation disappears. In France, the solar capture price doubled from 58 EUR to 118 EUR during cold periods. However, producers face volume risks, as they may be short on supply exactly when buying it back is most expensive.
9Storage and Trading Spreads
Cold spells shift the profitable trading window for battery storage. While the midday-to-evening spread narrows due to higher midday prices, the overnight-to-morning spread expands significantly. Batteries capable of cycling twice a day can capitalize on these shifting price dynamics, moving from solar-cycle trading to overnight-to-morning cycles during extreme winter cold.
10Historical Data and Trends
Analysis of eleven winters confirms that French cold is a predictable market variable. Since 2015, the French price response per degree has consistently stayed between 4% and 9% of the average winter price. This data allows market participants to better model price risks in Belgium, Germany, and other interconnected European power markets.
11Future Market Outlook
Two opposing forces will shape future winters. While a more robust French nuclear fleet could improve export consistency, the demand response per degree remains high at 1.9 GW. The balance between fleet availability and domestic demand will determine whether France remains an exporter or becomes a net importer during future cold snaps.
12Analytical Market Tools
Tools like WSP’s Electricity Market Outlook are essential for navigating these dynamics. By utilizing the PRIMES model, which has supported European Commission policy analysis for two decades, stakeholders can simulate all major European electricity markets simultaneously through 2050, helping to mitigate the risks associated with temperature-driven volatility and cross-border energy supply dependencies.
Original article: pv magazine — French Winter Cold and Its Impact on European Power Markets