The river flows in the southeast area of Sumatra, which has a predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification).[2] 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 May, at 25 °C.[3] The average annual rainfall is 3,248 mm. The wettest month being December, with an average of 547 mm rainfall, and the driest is September, with 40 mm of rain.[4]
