Rainfall simulation in centrifuge models is important for modelling soil–atmosphere interactions. However, the presence of Coriolis force, drag forces, evaporation and wind within the centrifuge may affect the distribution of rainfall over the model. As a result, development of appropriate centrifuge rain simulators requires a demanding process of experimental trial and error. This paper highlights the key factors involved in controlling rainfall in centrifuge simulations, develops a mathematical model to simulate rainfall within a centrifuge and shows how to calibrate it experimentally. Finally, the paper summarises some important factors that should be considered in the development of rainfall simulators for centrifuges.