Ulaanbaatar, Mongolia, has a cold semi-arid Köppen climate classified as BSk. The B identifies a dry climate, while S indicates steppe or semi-arid conditions and k signifies a cold version with a mean annual temperature below 18°C.
Ulaanbaatar’s climate reflects its unusual combination of high elevation, northern latitude, extreme continentality, and exposure to the Siberian anticyclone. The city lies hundreds of kilometres from the sea, so oceanic moderation is weak. Winters are long, dry, and intensely cold, while summers are short and comparatively warm.
Ulaanbaatar is often described as the world’s coldest national capital. A common mix-up is choosing BWk, which means cold desert; Ulaanbaatar is dry, but its precipitation is generally sufficient for the semi-arid steppe category rather than true desert. Some descriptions also note nearby continental or subarctic thermal boundaries, but BSk is the standard city classification.