In Intelligent Transportation Systems, visible light communication (VLC) has emerged as a powerful candidate to enable wireless connectivity in vehicle-to-vehicle (V2V) and vehicle-to- infrastructure (V2I) links. While VLC has been studied intensively in the context of indoor communications, its application to vehicular networking is relatively new. In this paper, we carry out a comprehensive channel modeling study to quantify the effect of rain and fog on a V2V link with a high-beam headlamp acting as the transmitter. Taking advantage of advanced ray tracing features, we first develop a path loss model for V2V link as a function of distance under different weather conditions. Then, we use this expression to determine the maximum achievable distance to ensure a given bit error rate. We further investigate the deployment of relay- assisted systems to extend transmission ranges. Extensive numerical results are presented to corroborate our findings.