A Semi-ari climate or steppe climate generally describes climatic regions that receive low annual rainfall (250-500 mm or 10-20 in). A more precise definition is given by the Köppen climate classification that treats steppe climates (BS) as intermediates between the desert climates (BW) and humid climates in ecological characteristics and agricultural potential. The Köppen climate classification allows adjustments for temperature and for excluding forested regions (such as those in most of Canada and Siberia).