Heat waves are becoming more frequent, intense, and longer-lasting due to the accelerating impacts of climate change. These extreme temperature events pose serious environmental, economic, and health threats, especially to vulnerable populations. This article investigates the science behind heat waves, their causes, and their wide-ranging effects on ecosystems, public health, urban infrastructure, agriculture, and water supplies. It also explores real-world case studies from around the globe and discusses the urgent need for adaptive strategies, such as early warning systems, sustainable urban planning, and international climate action. As global temperatures continue to rise, understanding and mitigating the impact of heat waves is crucial to protecting communities and the environment.