This paper was devoted to clarify and evaluate how fuel moisture content (FMC) characterising a homogeneous vegetation layer (grass or shrubs), can affect the behaviour of surface fire. The approach used in this study was based on numerical simulations performed using a detailed fire physical model. The numerical results were analysed in terms of fire residence time, fire front depth, mass loss rate and rate of spread (ROS). Two windy conditions (calm and weak) were studied to evaluate the decay of the rate of spread (ROS) resulting from an increase of the fuel moisture content. The effect of wind velocity upon marginal burning conditions was also analysed. The numerical results were compared with empirical data of the literature.