BWh represents a hot desert climate in the Köppen climate classification system.
The first letter B identifies dry climates, where potential evaporation is high relative to precipitation. The second letter W indicates a desert climate rather than a steppe climate. The lowercase h indicates a hot temperature regime, generally based on the system’s mean annual temperature threshold.
Köppen’s system was developed by climatologist Wladimir Köppen and first published in the late nineteenth century. It uses long-term temperature and precipitation patterns rather than a single season or weather event. The classification is therefore about climate, not day-to-day weather.
BWh is commonly associated with subtropical deserts, including parts of the Sahara and Arabian deserts, although exact classifications depend on local data and the version of the thresholds used. Af, by contrast, denotes a tropical rainforest climate, while Cfb commonly describes temperate oceanic climates.