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 September, when the average temperature is around 29 °C, and the coldest is March, at 22 °C.[4] The average annual rainfall is 2758 mm. The wettest month is January, with an average of 492 mm rainfall, and the driest is September, with 23 mm rainfall.[5]