Russia's climate is largely shaped by its enormous size and geography, where southern mountains block warm air from the Indian Ocean and open northern plains expose the country to Arctic and Atlantic influences, resulting in a dominant continental climate with warm summers and cold to very cold winters. This vastness creates a striking variety of regional climates, from the humid continental conditions of Moscow and Saint Petersburg to the subarctic climate of Siberia, the polar tundra along the Arctic coast, and even a humid subtropical zone in Sochi on the Black Sea. The far northeast is exceptionally harsh, with Yakutsk being the world's coldest major city and Oymyakon the coldest permanently inhabited settlement, where temperatures have plunged to a record -67.8°C. About 65% of Russian territory is underlain by permafrost, and while most areas see winter snow, the Lower Volga and Caspian coast experience semi-arid or arid conditions, while Kaliningrad enjoys a milder oceanic climate. Overall, the moderating influence of the Atlantic and Pacific oceans softens conditions in the west and east, but the interior remains subject to some of the most extreme temperature swings on Earth.