The river flows in the southern central area of Kalimantan with a predominantly tropical rainforest climate. The annual average temperature in the area is 22 °C. The warmest month is April when the average temperature is around 24 °C, and the coldest is December, at 21 °C. The average annual rainfall is 2778 mm. The wettest month is November, with an average of 386 mm of rainfall, and the driest is September, with 66 mm of rainfall.