Swiss nuclear reactors taken off grid as River Aare warms

Two nuclear reactors in Switzerland have been taken off the grid after rising river temperatures reduced the effectiveness of their cooling system, according to local media reports on Friday.

Energy company Axpo said the two Beznau reactor units, cooled by water from the River Aare, are now in a full shutdown state after being progressively reduced earlier in the week, according to SWI.

Axpo said the temperature of the River Aare reached 25C (77F), a level it said does not allow sufficient cooling for the plant's operations.

Output from the two reactors had already been reduced Tuesday, most recently to 50%. The company said the river reached 25C for the first time Wednesday after cooling water had been fully mixed, adding that if there was no prospect of the river cooling, the reactors would be shut down completely Friday.

The two units, located on the Aare island in Dottingen, had already temporarily suspended electricity production in July 2025.

Europe's current heatwave, which has brought red alerts to several countries throughout the week, is the "most severe" ever recorded in the region and was made significantly more likely and intense by fossil fuel-driven climate change, according to a report published Friday by World Weather Attribution (WWA).

The study found that the temperatures recorded would have been virtually impossible 50 years ago and far less likely even during previous record-breaking heatwaves.