The seasonal variability of the aerosol optical, microphysical and radiative properties at three insular sites in the western Mediterranean Basin is presented. The main drivers of the observed annual cycles and NE–SW gradients are mineral dust outbreaks in summer and European continental aerosols in spring. The lack of NE–W gradients of some aerosol properties is attributed to a homogeneous spatial distribution of the fine particle load and absorption low values in the southwesternmost site.