Main topics of driving assistances with respect to degraded driving situations, are low friction or low visibility. Thus, wind related problems are often less considered. However on high bridges or near sea shores, wind can generate car accident. In fact, wind shall have a huge impact on vehicle dynamic. For light vehicle, it could surprise the driver, resulting in a lateral movement. Looking at heavy truck, wind can be an additional factor that initiate a rollover. In this paper, an observer based method for the estimation of wind impact on vehicle dynamic is proposed. It develops the problem of numerical observability of the wind impact and propose an architecture to measure it. Next, it uses this knowledge in order to build a safe speed profile.