People enjoy swimming at Yeouido Hangang Park Swimming Pool in Seoul, June 21. Yonhap

Summer evenings are becoming prime swimming hours in Seoul, where thousands of residents are heading to Han River pools after sunset as the city extends operating hours to help people beat the heat.

The Seoul Metropolitan Government said Ttukseom and Yeouido swimming pools, along with the Jamsil and Nanji water playgrounds, have been operating nightly from 6 p.m. to 10 p.m. since July 3 and will continue through Aug. 30 without closing days.

The city said the nighttime program has proved popular as prolonged heat waves drive more people outdoors after dark.

"The night openings have transformed these public spaces into accessible, budget-friendly evening retreats for citizens escaping the heat," a city official said, noting that the combination of upgraded water infrastructure and cultural programming has made the riverside pools a centerpiece of Seoul's summer nightlife.