South Korea Faces Early Summer Heat And Showers

On Tuesday, June 17, 2025, South Korea braces for a day marked by sweltering early summer heat coupled with scattered showers and thunderstorms across various regions. The Korea Meteorological Administration (KMA) forecasts mostly cloudy skies nationwide, with the exception of Jeju Island, which is expected to enjoy mostly clear weather throughout the day.

Temperatures will climb to a daytime high ranging from 25 to 32 degrees Celsius, with Seoul reaching 30 degrees and Daegu slightly hotter at 31 degrees. This heat, combined with humidity, will push the sensible temperature in some areas even higher, such as Hapcheon in Gyeongnam Province, where it is expected to feel like 33 degrees Celsius. The early summer heat wave is setting in, signaling the start of what locals often call the “찜통 더위” or scorching heat.

Morning low temperatures across key cities will range between 18 and 22 degrees Celsius. For instance, Seoul will start at 21 degrees, Incheon at 20, and Jeju Island slightly warmer at 23 degrees. Daytime highs will vary regionally: Seoul at 30 degrees, Incheon at 26, Chuncheon at 29, Gangneung at 30, Daejeon at 28, Daegu at 31, Jeonju at 30, Gwangju at 31, Busan at 26, and Jeju Island at 29 degrees.

While the heat dominates, the weather will not be entirely dry. The KMA highlights the likelihood of strong showers accompanied by thunder, lightning, and gusty winds in several inland and mountainous regions. From morning through evening, areas including Gangwon Province’s inland and mountainous zones, Chungbuk, Jeonbuk inland, eastern Jeonnam, Gyeongbuk, and western inland Gyeongnam may see rainfall ranging from 5 to 40 millimeters. Specific expected rainfall amounts include 5 to 10 mm in Gangwon’s inland and mountainous areas, 5 to 10 mm in Daejeon and southern Chungnam inland, 5 to 30 mm in Jeonbuk inland and Gwangju, 5 to 40 mm in Daegu and Gyeongbuk, and 5 to 30 mm in western Gyeongnam inland.

According to the KMA, these showers will often be intense, with some regions experiencing strong downpours accompanied by thunder and lightning. The mountainous areas of Gangwon and northeastern Gyeongbuk are also expected to endure strong winds, with instantaneous gusts reaching up to 15 meters per second, and even up to 20 meters per second in higher elevations.

Sea conditions will be variable but generally moderate. Waves off the coasts of Incheon and northern and southern Gyeonggi will measure between 0.5 and 1.5 meters. Meanwhile, the East Sea and South Sea will experience waves ranging from 0.5 to 2.0 meters, with coastal waves near the shoreline possibly reaching 1.5 to 3.5 meters. In the southern seas near Jeju Island and the eastern South Sea, where a gale warning is in effect, winds will blow fiercely at 9 to 16 meters per second, producing waves as high as 4.0 meters.

Sea fog is also expected to develop in many maritime areas, particularly around islands where visibility could drop below 200 meters. This fog often comes with light drizzle, making navigation and outdoor activities near the coast potentially hazardous.

Air quality across the country remains favorable, with fine dust and ultrafine dust levels rated as “good” (좋음) nationwide. The ozone index is expected to stay within normal levels throughout the day, and yellow dust (Hwangsa) is predicted to be minimal, also rated “good.” Humidity will be relatively high in the morning, ranging from 60 to 95 percent, before decreasing to 40 to 80 percent by afternoon.

For residents and visitors, the KMA advises caution against heat-related illnesses as the heat intensifies. The agency recommends limiting outdoor activities during peak daytime hours, staying well-hydrated, and taking care to prevent food poisoning amid the warm temperatures. The heat impact forecast issued at 11:30 a.m. on June 17 will provide further guidance for those vulnerable to heat stress.

The day will begin with a sunrise at 5:10 a.m. in Seoul and will conclude with sunset at 7:56 p.m., giving South Koreans a full day to prepare for the mix of heat and showers. The Seoul metropolitan area, including Gyeonggi and Incheon, will start mostly cloudy but clear up by the afternoon, with temperatures ranging from morning lows of 19 to 22 degrees Celsius to highs reaching 25 to 30 degrees. Specific city forecasts include Suwon with 20 to 29 degrees, Seongnam 21 to 29, Gwacheon 20 to 30, Anyang 21 to 28, and Incheon 20 to 25 degrees.

Incheon’s coastal conditions will feature high tides at 8:29 a.m. and 8:51 p.m., with water levels reaching 832 cm and 726 cm respectively, and low tides at 2:18 a.m. and 3:00 p.m. with levels of 125 cm and 208 cm. These tidal variations, combined with the forecasted waves and sea fog, will be important considerations for maritime and fishing activities.

In summary, June 17, 2025, presents a complex weather picture for South Korea: a blend of early summer heat that pushes temperatures into the low 30s Celsius, intermittent but potentially heavy rain showers in many inland and mountainous areas, strong winds, and variable sea conditions. The KMA’s detailed forecasts and warnings underscore the need for vigilance regarding heat-related health risks and safety at sea and on land. As the country navigates this blend of heat and moisture, residents are encouraged to stay informed and take appropriate precautions to enjoy a safe and healthy day.