The river flows along the central north area of Java with predominantly tropical monsoon climate. The annual average temperature in the area is 25 °C. The warmest month is October, when the average temperature is around 28 °C, and the coldest is January, at 24 °C.[3] The average annual rainfall is 3459 mm. The wettest month is January, with an average of 713 mm rainfall, and the driest is September, with 33 mm rainfall.[4]