Abstract— Dynamic Thermal Rating (DTR) has gained increasing attention as a strategy to unlock additional transmission capacity by integrating real-time environmental conditions, in contrast to the conservative assumptions underlying Static Thermal Rating (STR). This paper presents one of the first empirical evaluations of DTR for the Nigerian grid, focusing on the Oshogbo–Ganmo transmission line in North-Central Nigeria. A Python-based simulation framework, aligned with the CIGRE standard, was developed using 2020–2021 historical load records, conductor parameters, and environmental variables, including wind speed, solar radiation, and ambient temperature. Results show that in over 99% of the study period, DTR values surpassed the actual load current, with line ratings often double or triple the STR. These outcomes reveal significant underutilized thermal headroom and demonstrate DTR’s potential to improve asset utilization, defer costly network reinforcements, and strengthen system reliability. By linking DTR deployment to the Nigerian context, this study contributes evidence on its feasibility in sub-Saharan grids and underscores its relevance to sustainable energy integration, aligning with UN Sustainable Development Goal 7 on affordable, reliable, and sustainable energy. Policy recommendations include real-time environmental monitoring infrastructure and the development of standardized DTR guidelines to facilitate large-scale adoption.