The Kualuh River is a river in northern Sumatra, Indonesia, about 1600 km northwest of the national capital Jakarta. The drainage area of 4,278 km<sup>2</sup> is mostly situated in North Labuhanbatu Regency of North Sumatra Province.
The river flows in the northern area of Sumatra with predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification). The annual average temperature in the area is 21 ðC. The warmest month is March, when the average temperature is around 26 ðC, and the coldest is October, at 20 ðC. The average annual rainfall is 3,730 mm. October is the wettest month with an average of 491 mm rainfall, and March is the driest, with 136 mm rain on average.