Different kinds of atmospheric media and variation of weather conditions make the generation of multi-spectral out-door scene image quite complex. In this paper, we propose a new approach to realistically generate the multi-spectral scene images under different weather conditions. We first establish the geometrical models of several special weather phenomena. The method of three-dimension cellular automata is adopted to construct the cloud, and particle system is used to model the rain. After that we calculate the radiance of different wavebands for cloud, fog, rain under different weather conditions. The radiance components, such as self-emitted radiance, reflected radiation, transmitted radiance, are calculated separately and the total radiance is thus acquired. Then, based on the spectral radiance values of cloud, rain and fog calculated by above models, we construct the scene under different weather conditions. Finally multi-spectral scene images under different weather conditions are rendered realistically. Simulation results show the potential of our approach.