Europe's June Heatwave Left 10,650 Excess Deaths — and Affected Power Markets

European countries recorded more than 10,000 excess deaths during the week of June 22–28, as a record-breaking heatwave swept France, Spain, Britain and neighboring countries, according to data from EuroMOMO, a mortality-surveillance network backed by the European Centre for Disease Prevention and Control (ECDC) and the World Health Organization (WHO). More than 9,000 of the deaths were among people aged 65 and older. Belgium and France recorded the highest "very high excess" mortality levels in the region, with Belgium reporting its highest heatwave-related mortality since national records began in 2000.

Scientists at Imperial College London, the UK Met Office and the London School of Hygiene & Tropical Medicine separately estimated 2,700 heat-related deaths in England and Wales across May and June, attributing 42% of those to additional heat associated with climate change.

Impact on energy markets: The heatwave also affected European energy markets. Electricity costs in Germany and France increased by a combined estimated €700 million during the peak week as cooling demand placed additional pressure on power systems. Belgium recorded a record quarter-hourly electricity price above €1,038/MWh. France's EDF temporarily shut down reactor units at the Golfech, Nogent-sur-Seine and Bugey nuclear plants after river water used for cooling became too warm, a challenge that has occurred during previous periods of extreme heat.

Broader context: The episode highlights how periods of extreme heat can affect electricity demand and generation across multiple markets. Higher cooling demand, lower thermal and nuclear generation efficiency, and weaker wind output during persistent high-pressure systems have also affected electricity grids in regions including Texas and California in recent years. EU policymakers have cited these challenges while advancing grid modernization and battery storage initiatives.

Sources: Reuters, EuroMOMO/ECDC, Euronews, Imperial College London