ABSTRACTSmall coastal islands serve as replicated units of space that are useful for studying community assembly. Using a unique database holding information on comprehensive vegetation surveys on > 840 small coastal islands fringing the whole continent of Australia, we investigated the extent to which conditions will change for plants on Australia's islands over the next 80 years in terms of their temperature envelopes and inferred changes in vapour pressure deficit (VPD). We found ~40% of island plant populations will experience mean annual temperatures beyond their current envelope. However, envelopes defined by VPD and extreme monthly temperatures are unlikely to be exceeded, highlighting islands' potential to act as climate refugia. Large species with slow life histories and poor dispersal traits were most likely to experience warmer temperatures, although this proved to be driven by correlations of these traits with latitude (closer to the equator) and with smaller range sizes. We found no evidence of warm edge extinction or poleward migration across species in response to 0.5° of warming since the year 2000. These results have applications for monitoring and conservation efforts under climate change for fragmented habitats everywhere.