The stochastic waves generated by storm landfalls usually determine the design and safety of coastal and offshore structures in typhoon regions. This study developed a parametric wave spectrum model for typhoon-generated stochastic waves that considers the variation in the wave spectrum due to the temporal variation in the typhoon. A field measurement campaign was conducted in nearshore strait water on the east coast of China to measure the wave data for two landfall typhoons: Soudelor and Dujuan. The measured wave data were filtered through a preprocessing framework. The parametric wave spectrum model was then developed based on the measured wave spectra for different stages of the typhoon. The main conclusions include the following: (1) 78% of the measured wave spectra at the example site under a typhoon are double-peaked, and approximately 15% are single-peaked; (2) the parametric model with either the Joint North Sea Wave Project (JONSWAP) or Ochi-Hubble (OH) kernel function is effective in defining the typhoon-generated wave spectra; and (3) the critical parameters of the developed model for typhoon-generated waves are site-specific and depend on the temporal variation of the typhoon.