A computer program was used to determine the effects of several variables on drift distances of spray droplets. Variables were initial droplet size, velocity and height of discharge, wind velocity and turbulence intensity, relative humidity, and volatility of the liquid. For relative humidity and wind velocity ranges of 20-80 % and 0.5-4.0 m/s, all 50 µm diameter water droplets directed downward with initial velocity of 20 m/s completely evaporated before depositing 0.5 m below point of discharge. With 20 m/s initial droplet velocity, 2.0 m/s wind velocity (20 % turbulence intensity) and 60 % relative humidity, 100 and 200 µm diameter droplets deposited 0.5 m below point of discharge at mean downwind distances of 2.6 and 0.13 m respectively. Drift distances of water droplets as large as 200 µm diameter were influenced by initial droplet velocity and height of discharge. Experimental data from tests in a wind tunnel verified the accuracy of the computer program in predicting drift distances of water droplets.