Dew is often present on foliage early in the morning when wind velocity may be at its lowest. The latter makes this time of day tempting for postemergence herbicide application to minimize spray particle drift. Herbicide applicators may not wish to wait to apply postemergence herbicide until the dew on the leaves dries. The objective of this study was to determine to what extent the dew affects the activity of postemergence application of glyphosate evaluated on velvetleaf, common lambsquarters, and giant foxtail. Glyphosate alone and with nine different adjuvant combinations was applied following dew formation. The observed glyphosate activity on these weeds differed very little between the no dew and the light dew treatments. The weeds with heavy dew generally had more injury from the various glyphosate treatments than those without dew. Certain adjuvant treatments markedly increased activity with heavy dew.