The intensifying heat stress poses significant risks to human health, particularly in already warm regions such as Southern Europe, Eastern Africa, and parts of Central America. Prolonged exposure to high heat and humidity can impair the body's ability to cool itself, increasing the risk of heat-related illnesses and fatalities. Vulnerable populations, including the elderly and outdoor workers, are especially at risk. The study also highlights the growing challenge of tropical nights, where minimum temperatures exceed 20°C, preventing adequate recovery from daytime heat. Without mitigation, these conditions could worsen, affecting billions globally.