Microclimate is the most appropriate measure of climate affecting species. Understanding microclimate variation is essential for predicting effects of climate change on species. This study examined (1) variation in microclimate temperatures associated with Azorella selago Hook. (Apiaceae) across Marion Island, (2) differences between microclimate temperature and meteorological station temperatures, and (3) effect of A. selago on microclimate temperatures. Microclimate temperatures were shown to vary significantly with altitude and island side. The microclimate associated with A. selago was also more extreme than meteorological station temperature ranges suggest. A. selago was shown to ameliorate temperature conditions compared to those on the ground. Given the biotic differences that have been documented between the sides of Marion Island, this finding argues strongly for improved understanding of spatial variability in Marion Island s climate. Such understanding is particularly critical given the rapid rate of climate change currently being experienced by the island.