Thunderstorm winds are characterized by significant low-frequency components or time-varying mean wind speed. In addition, the mean wind direction is time dependent. These are unlike the stationary synoptic winds which are commonly modeled with time-invariant mean wind speed and direction. We quantify the effects of the time-varying mean wind speed and direction, and the nonstationary fluctuating components of thunderstorm winds on the extreme peak wind pressure coefficient for a low building. For the quantification, we propose a simulation-based procedure and apply the equivalent-steady-gust model and the quasi-steady-vector model. The effect of the random orientation between the structural principal axis and the wind direction corresponding to the maximum mean wind speed (i.e., directionality effect) on the extreme peak wind pressure coefficient is also considered. By using the already available pressure coefficient obtained from the boundary layer wind tunnel tests, numerical analysis is carried out by considering the thunderstorm winds in the horizontal plane.