Urban stormwater runoff in China heats up from surfaces like roads and roofs. Different surface types affect runoff temperature during rain. Paved surfaces, like concrete, make runoff hotter at the beginning of rainfall. Rain intensity and previous weather also impact runoff temperature. Porous pavement can delay peak runoff heat. Features like bioretention cells cool runoff by sending it into the ground. Grass swales reduce runoff temperature better than hard surfaces, like asphalt or concrete. Overall, using low impact development tools can help cool down urban runoff and lessen environmental harm.