Air-cooled condensers (ACC) are commonly used for cooling applications in the petro-chemical and power generation industry. Common analysis techniques used include one-dimensional design codes, however, these fail to capture complex flow phenomena associated with ACCs subjected to adverse environmental conditions. Computational Fluid Dynamics (CFD) is seen as an alternative, more accurate analysis tool. The model used in the present study co-simulates the CFD using ANSYS Fluent® to model the air-side with a system-level model in Flownex® to represent the steam-side. A 4 × 3 ACC bank is subjected to adverse cross-wind conditions and a single cell is co-simulated. The volumetric and thermal performance is predicted. Prior to the evaluation a discretization process is undertaken to ascertain an adequate level of detail required to accurately capture the complex flow phenomena which could affect the steam-side performance. A 3 × 3 and 6 × 6 discretization case is compared. A 13% difference in heat transfer rate is predicted between the cases. The 6 × 6 case is used to evaluate the cell performance when the ACC is subjected to cross-wind speeds of 0, 3, 6 and 9 m/s. Results show an increase in outlet steam quality as the cross-wind speed increases due to diminishing ACC performance.