A general method to evaluate fluctuations of the semiclassical one-body Wigner function is presented both in the equilibrium and nonequilibrium framework. The model is valid far away from critical points, where the Boltzmann-Nordheim-Vlasov equation represents a good approximation of the average Wigner function. A first application of the model in momentum space is shown in comparison with different analytical results. An extension to realistic phase space calculations of heavy ion collisions is straightforward and numerically feasible. In this case, together with fluctations coming from the scattering processes, mean field fluctuations are automatically included. The role of Landau damping is discussed.