China lies mainly in the north temperate zone, characterized by a warm climate and distinctive seasons, with a climate well suited for habitation. From September to April the following year, dry and cold winter monsoons blow from Siberia and the Mongolian Plateau, resulting in cold and dry winters and great differences in the temperatures of north and south China. From April to September, warm and humid summer monsoons blow from the seas in the east and south, resulting in overall high temperatures and plentiful rainfall, and little differences in the temperatures of north and south China. In terms of temperature, the nation can be sectored from south to north into equatorial, tropical, subtropical, warm-temperate, temperate, and cold-temperate zones. Precipitation gradually declines from the southeastern coastal areas to the northwestern inland areas , and the average annual precipitation varies greatly from place to place. In southeastern coastal areas, it reaches over 1,500 mm, while in northwestern areas, it drops to below 200 mm.