The river flows in the central area of Java with a predominantly tropical monsoon climate (designated as Am in the Köppen-Geiger climate classification).[3] The annual average temperature in the area is 21 °C. The warmest month is September when the average temperature is around 24 °C, and the coldest is June, at 20 °C.[4] The average annual rainfall is 3140 mm. The wettest month is January, with an average of 560 mm of rainfall, and the driest is September, with 14 mm of rainfall.[5]