The aim of the study was to estimate the range of climate variability during the Ferdynandovian climatostratigraphic unit (MIS 13–15). The studied pollen sequences encompass two interglacials (Ferdynandovian I and II — F I and F II), the glaciation separating them (F I/II), the late glacial of the Sanian I (=Elsterian 1) and the early glacial of the Sanian II (=Elsterian 2) and are correlated with the Cromerian Complex in Western Europe. The modern analogue technique and plant indicator taxa method are applied to two high resolution pollen records (Zdany and Łuków-3a) from E Poland to infer total annual precipitation, mean annual temperature and temperatures of the warmest and the coldest months. The results of the two methods create a coherent picture of climate changes.The succession starts with steppe–tundra and boreal forests, reflecting a cool, late glacial continental climate and develops into widespread Ulmus and Quercus dominated communities, followed by Corylus expansion in warm (at least 18°C in July), oceanic conditions (~800–900mm annual precipitation) during the first interglacial optimum (F I). The cold, continental climate of the glaciation (F I/II) with annual precipitation of ~420mm and mean January temperature less than −12°C separated the two interglacials. The second interglacial (F II) characterized by Carpinus dominated forests was found to be warm (mean July temperature up to 19°C) but slightly less oceanic, which is consistent with the scarcity of indicators of a warm and humid climate. Principal components analysis (PCA) confirmed the distinctive climatic features of the two interglacials and showed that the cooling F I/II has palynological characteristics similar to the stadial/interstadial changes within the Sanian I and Sanian II glaciations.