Extreme heat is reshaping life in cities. For millions of people, especially in fast-growing urban areas of the Global South, higher temperatures are making it harder to earn a living, attend school, access healthcare, or move safely throughout the day. Extreme urban heat and lack of sustainable cooling is threatening productivity, deepening inequality, and increasing the risk of displacement when communities can no longer cope. Cities cannot afford to treat extreme heat as a seasonal inconvenience. Without action, heat will erode livelihoods and overwhelm urban infrastructure and services. It will fuel unemployment, drive internal and cross-border migration, and put massive demands on energy systems. Cities must act now to manage rising temperatures before it is too late. The Handbook on Urban Heat Management in the Global South, developed by the World Bank in partnership with the United Nations Human Settlements Programme (UN-Habitat) and the United Nations Environment Programme (UNEP), offers a practical response. It brings together real examples and strategies from cities that are already tackling extreme heat. It focuses on powerful solutions that are feasible, affordable, and easy to adapt – especially those that expand access to accessible, sustainable cooling.