Marine areas are affected by different atmospheric phenomena such as wind and storm. In this research the effect of a large scale atmospheric phenomenon, known as Winter Shamal Wind, is investigated on the regime of currents and waves in the northwest part of the Persian Gulf. This wind normally occurs for the period of three to seven days, during December to early March. MIKE21 Coupled Model FM was applied to study the pattern of current and waves for this period. To provide the hydrodynamic data for the model and validate the simulated results, the wind data of ECMWF and mast meteorology of coastal synoptic station of Bushehr and wave data of buoy located offshore of Bushehr was used. The results indicated only a slight increase in current speed with no significant change in current direction during Winter Shamal Wind, showing a stable current pattern in northwest of the Persian Gulf. The significant wave height and wave propagation speed for the period of Winter Shamal Wind in comparison with the days prior to the wind show significant changes. The maximum wave speed in the area under investigation reaches up to 1 m/s and the significant wave height is almost 1 meter higher than that of normal situation.