Rokan-kiri River is a river in Riau province, central part of Sumatra island, Indonesia, about 1,100 km northwest of the capital Jakarta.

The river flows in the central area of Sumatra, which has a predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification).

The warmest month is August, when the average temperature is around 24 °C, and the coldest is January, at 22 °C.

[4] The average annual rainfall is 2742 mm.

The wettest month is November, with an average of 401 mm of rainfall, and June is the driest, with 85 mm of rain.