A roadside display shows the temperature at 38 C in Seodaemun-gu, Seoul, on Friday. (Yonhap) Temperatures in parts of Seoul surpassed 40 degrees Celsius on Friday for the first time in eight years, as extreme heat continued across South Korea ahead of a modest easing expected over the weekend.An automatic weather station in Nowon-gu, northeastern Seoul, recorded 40.2 C at around 3:30 p.m., according to the Korea Meteorological Administration.It was the first reading above 40 C at a Seoul observation point since Aug. 1, 2018, when an automatic station in Gangbuk-gu recorded 41.8 C.The Nowon reading does not represent Seoul’s official temperature, which is measured at the Seoul weather station in Jongno-gu. The official temperature reached 38 C on Friday. Seoul’s record official high remains 39.6 C, set in 2018.Temperatures climbed even higher elsewhere, with Hanam in Gyeonggi Province reaching 40.7 C and Gwangyang in South Jeolla Province hitting 40.2 C. Yeongwol in Gangwon Province reached 39.8 C.The KMA has issued its highest-level heat warning for parts of the Seoul metropolitan area, inland Gangwon Province and the Jeolla region, with the alert expanded Friday to parts of Daegu and North Gyeongsang Province.The prolonged heat has also made this summer one of the hottest on record. From June 1 through Thursday, South Korea recorded an average of 14.8 heat-wave days, defined as days with highs of at least 33 C. That was the fourth-highest figure for the period since nationwide weather observations were expanded in 1973.The average number of tropical nights over the same period reached a record 13 days. A tropical night is recorded when the overnight low remains at or above 25 C.The heat has taken a growing toll on public health. A total of 208 heat-related illness cases were reported Wednesday, bringing the cumulative number to 2,665, including 23 deaths, according to the Central Disaster and Safety Countermeasures Headquarters.The most extreme heat is expected to ease somewhat over the weekend, though much of the country will remain hot. Daytime highs are forecast at 26 C to 35 C on both Saturday and Sunday.