Two data sets representing atmospheric moisture are available for the high Andes of Ecuador, (i) cloud frequency obtained from weather satellites, and (ii) interpolated rainfall estimates obtained from global climate observations. We analyzed their correlation to vascular plant species composition at 18 Ecuadorian superpa´ ramo study sites. Of
particular interest was whether cloud frequency could be used as a proxy for precipitation. Cloud frequency had distinct seasonal and spatial variation among the sites. The spatial gradient of cloudiness was strongest during JuneAugust and weakest around the equinoctials. Interpolated rainfall estimates also showed seasonal and spatial
variation among the sites, but there was no correlation between them and cloudiness. Cloud frequency during JuneAugust was the only significant variable in the canonical correspondence analysis (CCA) of the species composition, whereas rainfall estimates, geology, presence of glaciers, and size and altitudinal range of the superpa´ ramos were not significant. When the spatial components were filtered out from the species composition data by employing partial CCA, cloud frequency during DecemberFebruary became the only significant variable. Our results suggest that cloud frequency data may be a useful tool in mountain ecology research, serving as an indicator of habitat humidity when exact precipitation data are lacking.