This study examined the capability of the GFS-WRF-SWAN system by comparison of predictions with observations. Firstly typhoon courses were estimated from GFS and compared with observed courses together with forecasted ones by Japan Meteorological Agency. Secondly estimated wind fields around the Mutsu Bay, by WRF, were compared with the observations. It was found that GFS's and WRF's predictions showed fairly good agreement for both cases. Finally GFS-WRF-SWAN wave predictions were compared with observations. Concerning with the time series, there can be seen good agreements; however, the predicted wave heights were smaller than observations. It was also found that options of INPUT BY WIND in SWAN and a setting of frequency range affect wave predictions.