The importance of heat stress in public and occupational health in South Asia is now generally recognized. The region experiences a monsoonal climate, resulting in a stark contrast between dry and wet seasons. This strong seasonality leads to a heat exposure pattern in South Asia that differs from regions without a monsoonal climate. To identify and evaluate adaptation measures for extreme heat, it is essential to understand both the meteorology of extreme heat and its impacts on the human body. This chapter provides an overview of both aspects—meteorology and impacts—with the aim of delineating areas of significant overlap. It then outlines challenges that must be addressed to improve systems-level forecasting and adaptation to extreme heat in a changing climate in South Asia.