The river flows in the northwest area of Java with predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification).[3] The annual average temperature in the area is 26 °C. The warmest month is August, when the average temperature is around 28 °C, and the coldest is April, at 24 °C.[4] The average annual rainfall is 3674 mm. The wettest month is December, with an average of 456 mm rainfall, and the driest is September, with 87 mm rainfall.[5]