In the summer of 2003, Europe was gripped by a heatwave of unprecedented intensity. For weeks, a high-pressure system trapped hot air over the continent, pushing temperatures beyond 104°F (40°C) in countries like France, Italy, and Spain. The relentless heat turned cities into ovens, strained hospitals, and withered crops across vast regions. By the time it ended, the heatwave had claimed an estimated 70,000 lives, making it one of the deadliest climate-related disasters in modern history. The elderly, isolated, and vulnerable were hardest hit, many dying quietly in stifling apartments without air conditioning. In France alone, nearly 15,000 people perished in August. The disaster also left deep environmental and economic scars. Rivers shrank, nuclear plants cut output, and wildfires consumed thousands of square miles of forest. Agriculture suffered devastating losses, costing Europe more than $15 billion. The 2003 heatwave was a wake-up call, widely linked to climate change, and it forced governments to rethink preparedness. Many countries introduced heatwave response plans, early warning systems, and cooling centers. While later heatwaves would come, none would find Europe as unprepared again. This episode highlights not only the immense toll of that summer but also the urgent reality that extreme heat, once rare, is becoming the new normal in a warming world.