Straddling the equator, Indonesia has a tropical climate characterized by heavy rainfall, high humidity, high temperature, and low winds. The wet season is from November to March, the dry season from April to October. Rainfall in lowland areas averages 180–320 cm (70–125 in) annually, increasing with elevation to an average of 610 cm (240 in) in some mountain areas. In the lowlands of Sumatra and Kalimantan, the rainfall range is 305–370 cm (120–145 in); the amount diminishes southward, closer to the northwest Australian desert. Average humidity is 82%.
Altitude rather than season affects the temperature in Indonesia. At sea level, the mean annual temperature is about 25– 27° C (77–81° F ). There is slight daily variation in temperature, with the greatest variation at inland points and at higher levels. The mean annual temperature at Jakarta is 26° C (79° F ); average annual rainfall is about 200 cm (79 in).