 Hydropower plays a key role in the transition towards a low-carbon power system, but its reliance on local weather conditions and climate variability means it must be supplemented by other sources of renewable energy, such as solar and wind power. Extreme climate conditions, such as hot dry compound events, can have a major impact on hydropower production, particularly in countries like Switzerland where hydropower provides the majority of electricity generation. Our research shows that run-of-river schemes with limited water storage capacity are most vulnerable to hot dry conditions, while those with larger reservoirs and glacial resources are better equipped to cope with these conditions. This suggests that hydropower should be integrated into a wider portfolio of renewables, including solar and wind, to ensure reliable and sustainable energy supply. This article was authored by Noelia Otero, Pascal Horton, Olivia Marcius, and others.