Abstract: Dynamic Line Rating (DLR) refers to the change in the thermal ratings of power transmission lines in response to environmental conditions, such as temperature. With more stressed grid conditions, it is critical to investigate the impacts of considering DLR in an Optimal Power Flow (OPF) solution, particularly for systems with a high penetration of renewable energy systems. This study aims to demonstrate the impacts of DLR on N−1contingency analysis and OPF under high penetration of renewable energy and various load levels. Due to the intermittent nature of renewable energy sources (RES), a probabilistic OPF approach is developed to further investigate the impacts of DLR while accounting for RES uncertainties. Case studies on a modified IEEE 118-bus system with real-world data demonstrate that DLR effectively eliminates the issues of line congestion, reduces instances of bus voltage violations, and lowers the total generation cost. Hence, the impact of DLR on system planning becomes increasingly salient as RES levels increase.