Imperial Grantham Institute – Climate Change and the Environment, July 2025

Climate change tripled heat-related deaths in early summer European heatwave

Many cities in Europe experienced the first extreme heatwave of the summer in the last week of June and the first days of July 2025, after an exceptionally warm June with several heat records being set across European cities. Schools in parts of France had to be closed and outdoor working was banned during the hottest parts of the day in Italy (The Guardian, 2025). Serbia for example, has recorded its hottest day of the 19th century since the recordings began (Politico, 2025). Despite it still being early in the season, it was already the second time amber health alerts were issued in the South East of the UK, while cities across the continent saw even more severe health warnings, including Paris, Rome, Milan, Sassari, Lisbon and several cities across the Balkans (BBC, 2025).

The persistent heat was driven by a high-pressure system over Western Europe, commonly referred to as a heat dome. This system acts like a lid, trapping hot, dry air beneath it and causing temperatures to rise over time. As the system moved eastward, it was also pulling in hot air from North Africa, gradually intensifying the heat across the region. Li et al., 2025 suggests that the heatwaves associated with these weather patterns are becoming more frequent and intense due to climate change.