What Köppen climate code represents a hot desert climate? The answer is BWh.
The code belongs to Köppen’s dry-climate group, marked by the first letter B. The second letter W means desert, distinguishing it from S, which means semi-arid or steppe. The final letter h identifies a hot version, generally associated with a mean annual temperature above 18°C.
Hot deserts commonly occur beneath subtropical high-pressure belts, where descending air suppresses cloud formation and rainfall. The Sahara, Arabian Desert, interior Australia, and parts of the southwestern United States contain extensive BWh regions. Some coastal deserts, such as the Atacama, can also be classified as BWh despite cool ocean currents and frequent fog.
A common mix-up is BWk, which means cold desert climate. The Gobi is a familiar BWk example: it is arid, but its continental setting produces much colder winters. BSh and BSk are semi-arid steppe climates, so they receive more precipitation than true BW deserts.