Serang River is a river in northern Central Java, Indonesia, about 400 km east of the capital Jakarta.

[1][2] The largest tributary is Lusi River, which discharges into Serang River after passing the city of Purwodadi.

[3] The river flows in the central area of Java with predominantly tropical monsoon climate (designated as Am in the Köppen-Geiger climate classification).

The warmest month is October, when the average temperature is around 28 °C, and the coldest is January, at 23 °C.

The wettest month is January, with an average of 527 mm rainfall, and the driest is September, with 35 mm rainfall.