Since the effects of external conditions, such as limited resource supplies and poor working environments in damaged regions, are critical to facility restoration projects after a catastrophic disaster, a lack of understanding regarding restoration conditions may lead to unexpected delays and additional project costs. The fact that various elements of postdisaster restoration conditions interact with each other and vary with a facility's surrounding damage and recovery situations over time makes many stakeholders' comprehension even more challenging. To support immediate and appropriate facility restoration planning under changing project conditions, this study developed a hybrid system dynamics (SD)-discrete event simulation (DES) framework. In this hybrid restoration simulation, SD allows for a comprehensive understanding of the dynamic features of various restoration conditions, while DES enables an in-depth examination of facility restoration operations according to external condition changes. By allowing two simulations to seamlessly interact together, this study provides key insights into postdisaster restoration, including how complex and critical restoration conditions change over time depending on facility types and subregions, and to what extent these conditions adversely impact a project's performance and uncertainty throughout lengthy project durations, especially when restoration work scope and processes vary with damage patterns. A test tool for analyzing the effectiveness of managerial policies is also provided by showing experimental results. For instance, a project initiation, postponed to avoid unfavorable restoration conditions, can be delayed to reduce the project's uncertainty by alleviating possible increases in wasted time and cost of running an unproductive site. Therefore, the major contribution of this research to the body of knowledge in construction engineering resides in the capacity for the developed hybrid model to make facility restoration planning and execution deal with project uncertainties caused by chaotic and disrupting external conditions. As such, unexpected delays and additional costs common for postdisaster recovery can be alleviated.