This article examines how escalating heatwaves—intensified by recent record-breaking global temperatures—pose serious threats to rapidly urbanizing cities in Latin America, Africa, and tropical regions. These metropolises often face fragile infrastructure, including inadequate sanitation, unreliable energy systems, and strained healthcare networks, all of which are vulnerable to heat-related stress. The interaction between water shortages, energy failures, and public health breakdowns can amplify the impact of extreme heat, increasing risks of disease and mortality. The article critiques reliance on individual household adaptations, such as private wells and water storage, which mask deeper systemic vulnerabilities. It calls for urgent investments in resilient, integrated infrastructure and emphasizes the need for inclusive, community-based approaches to planning. Promoting equity and addressing service interdependence are essential to ensuring that the most vulnerable populations are protected in a warming world.