Plant macrofossils from permafrost deposits at the Bolshoy Lyakhovsky Island, New Siberian Archipelago, in the Russian Arctic were studied aiming at the revelation of climatic similarities and distinctions between the last and the current interglacial. The plant remains revealed the existence of a shrubland dominated by Alnus fruticosa, Betula nana, and Ledum palustre and interspersed with lakes and grasslands during the last interglacial. The reconstructed vegetation differs fundamentally from the high arctic tundra that exists in this region today, but resembles an open variant of subarctic shrub tundra as occurring near the tree line about 350 km southwest of the study site. Such difference in the plant cover implies that, during the last interglacial, the mean summer temperature was considerably higher, the growing season was longer, and soils outside the range of thermokarst depressions were drier than today. Pollen-based climatic reconstructions using the best modern analogue (BMA) approach suggest a mean temperature of the warmest month (MTWA) range of 914.5 °C during the warmest interval of the last interglacial. Reconstructions from plant macrofossils based on thermal minimum needs of included plants, representing more local environments, gained MTWA values above 12.5 °C in contrast to todays 2.8 °C. We explain this contrast in summer temperature and moisture conditions with a combination of summer insolation higher than present and climatic continentality in arctic Yakutia stronger than present as result of a considerably less inundated Laptev Shelf during the last interglacial. The project was funded by the German Research Foundation (DFG).