Extreme heat is becoming one of the most lethal and underestimated threats to cities in Europe and Central Asia, exacerbating health risks, undermining productivity, and pushing infrastructure to its limits. This report presents new analysis showing that without urgent adaptation, heat-related deaths could double or triple, and economic losses could reach 2.5% of GDP by mid-century. The report identifies cities as both the frontline victims and potential leaders in building resilience, offering a roadmap of practical, high-impact actions. With targeted investments, cities can cool their environments, protect vulnerable populations, and safeguard economic performance in an increasingly hotter world.