Wind erosion is a dominant geomorphological process in arid landscapes. It contributes to the loss of soil resources and the emission of mineral dust, with major impacts on regional climate, biogeochemical cycles and human health. Wind erosion occurs when the wind speed exceeds a certain threshold value, which depends on a number of factors including surface soil moisture. Through this control on the threshold velocity, hydrological processes affect the soil’s susceptibility to wind erosion and the rate of sediment transport. In arid regions the atmospheric humidity plays an important role in determining both the surface moisture content and the threshold shear velocity. The dependence of threshold velocity on near surface air humidity and fire-induced water repellency is discussed using a series of wind tunnel tests, laboratory measurements, and theoretical frameworks.