Little is known about the long-term Quaternary climate evolution of central and southeast Europe, because suitable terrestrial paleoenvironmental records are scarce. We present a multiproxy record of loess paleosol sequences in the Middle and Lower Danube Basins over the past 700 k.y. In these lowlands, the continentality of interglacial climate progressively increased during the Middle Pleistocene. Corresponding trends are seen in other climate proxies in the same region and in the lowlands of the northern Black Sea, but not, or less clearly, in climate archives from outside these lowlands. We conclude that a small-scale increase in paleoelevation of central European mountain ranges (the Alps, Carpathians, and Dinarides) during the Middle Pleistocene might be the cause of the progressive increase in climate continentality of southeast European lowlands.