moderately dry climates; usually not as dry as arid climates, but usually not as wet as temperate climates.

Semi-arid generally describes climatic regions that receive low annual rainfall (250-500 mm or 10-20 in) and have predominantly scrub or short-grass vegetation. A more precise definition is given by the Köppen climate classification that treats steppe climates (BS) as intermediates between the true deserts (BW) and humid climates in ecological characteristics and agricultural potential. The Köppen climate classification allows adjustments for temperature and for seasonality of precipitation, effectively excluding forested regions (such as those in Canada and Siberia).