The riverflows in the northern area of Sumatra with predominantly tropical rainforest climate. The annual average temperature in the area is 22 °C. The warmest month is March, when the average temperature is around 23 °C, and the coldest is June, at 21 °C. The average annual rainfall is 2943 mm. The wettest month is December, with an average of 370 mm rainfall, and the driest is June, with 82 mm rainfall.