A water sprinkler truck sprays water onto a road in Seoul's Mapo District, Thursday, as the city sweltered under a heat wave that pushed daytime temperatures to 39 degrees Celsius. Yonhap

The scorching heat wave in Korea is expected to reach its peak, Friday, before easing slightly over the weekend, although forecasters warned that temperatures will remain well above seasonal averages and the respite is likely to be short-lived.

The Korea Meteorological Administration (KMA) forecast Seoul's daytime high to remain at 39 degrees Celsius, Friday, after reaching the same temperature, Thursday, leaving it just 0.6 degrees Celsius shy of the city's all-time record of 39.6 degrees Celsius, set on Aug. 1, 2018.

The agency said temperatures could again exceed 40 degrees Celsius in parts of the capital region after topping that mark, Thursday, while widespread tropical nights — when overnight lows remain above 25 degrees Celsius — are expected to persist.

Elsewhere, daytime highs are forecast to reach 38 degrees Celsius on Friday in Incheon and Gwangju, 37 degrees Celsius in Daejeon and Daegu, 35 degrees Celsius in Busan and 34 degrees Celsius in Ulsan.