One of key factors in simulating offshore wind field is con- sidering the effects of waves on momentum and energy ex- changes between the atmosphere and ocean. However, most NWP models traditionally overlook the effects of waves, due to the lack of suitable roughness length parameterization. To address this issue, coupling atmospheric and wave mod- els has emerged which handles the wind-wave interaction through the exchange of a few quantities between two mod- els. On the other hand, integrating atmospheric and wave models requires substantial computational resources and as- sociated expenses. In this study, we developed an offline wave coupling method in the WRF to account for wave ef- fects on wind field simulations. With this method, the WRF is modified to read wave parameters and bathymetry data, and to parameterize roughness length using these data. Our study aims to evaluate the offline method by comparing it to an online coupling system that uses the coupled atmosphere and wave models, as well as observation data. We found that the offline method utilizes almost 17% fewer computational resources and 19% less computational time compared to the online method, while maintaining identical forecasting accu- racy. Evaluation of the results during dominant swell con- dition suggested that both methods are able to reduce the forecast uncertainty compared to LiDAR measurement spe- cially in the lower part of atmosphere.