This chapter investigates passive climatic adaptation strategies embedded in the traditional of Bushehr, a coastal city on the Persian Gulf. Drawing on empirical fieldwork, historical analysis, and CFD simulations, the study explores how vernacular design elements—such as compact morphology, narrow alleys, open squares, wind-oriented passageways, and local building materials—support natural ventilation and thermal comfort in hot–humid environments. Airflow behavior was analyzed across cross-sections and observation points using ANSYS Fluent, revealing critical relationships between urban form and wind velocity, pressure distribution, and ventilation effectiveness. Findings demonstrate that open spaces, height differentials, rooflines, and spatial connectivity significantly enhance airflow performance at both pedestrian and upper levels. The study further reflects on the deterioration of traditional passive systems under modern interventions, advocating for the reintegration of vernacular strategies into contemporary urban design. The results provide evidence-based insights into energy-efficient, climate-responsive planning in rapidly urbanizing regions facing increasing thermal stress.