Spray dispersal was measured from overlaid crosswind swaths applied using an aerial silvicultural herbiciding method under various meteorological conditions. Spray applications were made with D8-46 hollow-cone nozzles mounted on a C188 fixed-wing aircraft flying at 45 m s −1, from which a simulant tank mix was applied at 30 l ha −1 and an equivalent glyphosate application rate of 1.8 kg ha −1. Spray lines were released at 10 m above ground over a short, open forest canopy in neutrally-stable and unstable atmospheric boundary layers with average wind speeds and air temperatures of 1.5–3.1 m s −1 and 15–20°C at release height. Peak deposits on ground plates and artificial foliage at 2 m above ground averaged 57 and 36% of the glyphosate application rate, occurring at downwind distances of 0 and 10 m, respectively. Deposits decreased by 90% between 0 and 50 m downwind, but showed a more gradual decrease between 50 and 200 m downwind to an average of 0.3 and 0.2% of the application rate for ground plates and artificial foliage, respectively. Up to sevenfold differences in deposit were observed at a given downwind distance under different meteorological conditions. The volume median diameters on ground cards and artificial foliage averaged 425 and 419 μm respectively at 0 m, and 103 and 79 μm at 200 m. Number median diameters on ground cards and artificial foliage averaged 252 and 197 μm respectively at 0 m, and 55 and 45 μm at 200 m.