While temperature effects on species’ vulnerability to climate change are well studied, desiccation effects receive comparatively little attention. In addition, we poorly understand the capacity of ectotherms, and especially reptiles, to control water loss rates behaviourally by selecting suitable microhabitats. Such behavioural hydroregulation and trade-offs between desiccation avoidance and selection of optimal temperatures may greatly affect species’ fitness under climate change by limiting potential activity times and by placing individuals in a thermally suboptimal microhabitat. This study examined water loss rates and behavioural hydroregulation in a tropical rainforest skink and found evidence that higher temperatures elicited humid refuge choice despite placing individuals in suboptimal thermal conditions, as indicated by their range of preferred body temperatures. This novel finding emphasizes the importance of water loss even for taxa traditionally assumed to be highly desiccation resistant, and highlights this factor’s potential influence on vulnerability to climate change.