A heat wave that had persisted mainly across the Yeongnam region spread westward along east winds, prompting the first-ever severe heat warning for Seoul and the greater metropolitan area. Seoul recorded 36.7 degrees Celsius on this day, setting a new year-high temperature. The heat wave also continued in the Yeongnam region, with Daegu recording its second-highest temperature since 1942.
On the 3rd, the Seoul Metropolitan Meteorological Administration issued a severe heat warning at 4 p.m. for Seoul's southeast and southwest districts, as well as Hanam, Osan, and western Yeoju in Gyeonggi Province. The warning takes effect from 11 a.m. on the 4th. The severe heat warning is the highest level of the heat advisory system newly established this year. It is issued when there is a markedly high risk of serious harm, including deaths, to the entire population, including healthy individuals, due to an unusual heat wave. This is the first time a severe heat warning has been issued for Seoul and the greater metropolitan area. The meteorological agency explained the basis for the announcement, saying, "On the 4th, the daily maximum apparent temperature and maximum temperature are expected to exceed 38 degrees and 39 degrees, respectively."
Heat-related illness cases have indeed been occurring one after another in Seoul. According to official statistics released by the Korea Disease Control and Prevention Agency on the 3rd, 18 heat-related illness cases were reported in Seoul the previous day. Since May 15 this year, cumulative heat-related illness cases total 185, including two deaths.
On this day, Seoul recorded 36.7 degrees at the Automated Synoptic Observing System (ASOS), marking the hottest day of the year so far. In particular, some areas such as Geumcheon-gu, Guro-gu, and Gangnam-gu saw temperatures soar to around 38 degrees at Automatic Weather Stations (AWS). Some parts of the metropolitan area, including Hanam and Gapyeong in Gyeonggi Province, also recorded temperatures around 39 degrees.
The heat wave, which had been raging in southern areas such as Yangsan in South Gyeongsang Province, began to spread in earnest to western regions, including the metropolitan area, from this day. The center of the heat wave shifted westward because the wind blowing inland across the Korean Peninsula changed from a southwesterly to an easterly wind, bringing regions west of the Baekdudaegan mountain range, including the metropolitan area, under the influence of the "foehn phenomenon." Wind blowing from the east became hot and dry as it crossed the mountain range, driving up temperatures in the western regions. The meteorological agency analyzed that the fact that the North Pacific high-pressure system and the Tibetan high-pressure system layered over the skies of the Korean Peninsula, preventing hot air from escaping, also intensified the heat wave.
The heat wave in the southeastern part of the Korean Peninsula also continued. In particular, record-breaking heat continued in areas with basin topography where heat does not easily escape. On this day, the daytime high temperature at the Daegu weather observatory rose to 39.6 degrees. This was the second-highest level since 40 degrees was recorded on August 1, 1942. Gwangyang in South Jeolla Province also recorded 41 degrees as heat was trapped in the basin topography and hot sea breezes flowed in from the high water temperatures of nearby waters. This was the highest level nationwide on this day.
The meteorological agency forecast that the sweltering heat, with maximum apparent temperatures around 35 degrees, will continue in most regions nationwide for the time being. On the 4th, the morning low is expected to be 23 to 27 degrees, and the daytime high 31 to 37 degrees. The heat wave is likely to continue into next week, possibly lasting until around the 13th.
From the afternoon of the 4th, there is news of showers in areas such as southern Gyeonggi, the Chungcheong region, the Jeolla region, and the western inland areas of Gyeongsang, but with most areas expected to see about 5 to 40 millimeters of rain, it is expected to be insufficient to cool the heat. In particular, after the rain stops, humidity is expected to rise, driving the apparent temperature back up.
