SEDFAL, a numerical model of windblown seed dispersal, simulates seed release as a function of humidity and wind speed for each month of the dispersal interval. Seed terminal velocities are parameterized as a 10-bar histogram, and winds are described according to their frequency of occurrence in 10 wind-speed, 16 direction, and 5 vapor pressure deficit classes. The simulated seed dispersal pattern is summarized numerically, and may be displayed in printer plot form or plotted on a graphics device, with or without numerical smoothing, at the user's discretion.