France Cuts Nuclear Output Amid Mediterranean Heatwave – Water 5°C Above Normal

Cologne - As part of the European Union's Copernicus program, a recent analysis of water temperatures in the Mediterranean has revealed an exceptional heatwave. The temperature distribution for the western Mediterranean and southern France on June 22, 2025 indicates values that are up to 5 degrees Celsius above the seasonal average.

The Spanish weather service AEMET also reports unusually high temperatures in the Mediterranean and on the Spanish coasts. Temperatures in the Mediterranean exceeded 25 degrees Celsius as early as mid-June. This value already corresponds to typical July temperatures.

The persistent heat in the western Mediterranean region forced the French state-owned energy supplier EDF in southern France to reduce electricity production in several nuclear power plants as early as the end of June 2025. This is due to excessive water temperatures in the rivers that are needed to cool the reactors.

EDF has already issued several warnings as a result of the heatwave, including on the French mainland. Most recently, the Blayais nuclear power plant site near Bordeaux, where four reactors with a total output of 3,600 megawatts are in operation, was affected. Due to the expected high temperatures in the Gironde region, there may be power restrictions from Monday, June 30, 2025, according to EDF. The forecasts will be continuously monitored and adjusted.

EDF had previously also issued warnings for the Bugey and Golfech nuclear power plant sites. The Bugey nuclear power plant with four reactors and a capacity of around 3,600 megawatts is located on the Rhone. The Golfech site, with two reactor units of 1,360 megawatts gross each and a total output of 2,700 megawatts, is located in the municipality of the same name in south-west France, directly on the Garonne between Toulouse and Agen.

Source: IWR Online, 26 Jun 2025