# South Korea extreme summer weather: Heat, floods, and flux > Live situation record from CLSTR: https://clstr.news/situations/south-korea-heatwave-june-2026 > Updated: 2026-09-09T22:00:00.000Z. Sources: 69. Developments: 36. The extreme weather patterns of summer 2026 in South Korea have been characterized by intense heatwaves, localized heavy rainfall, and regional droughts. The Korea Meteorological Administration reported a national average temperature of 25.4 °C, the third highest since 1973. Temperatures exceeding 39 °C were recorded 42 times across 83 observation points, including a record 42.5 °C in Yangsan. Additionally, the national average for tropical nights reached 18.2 days. While overall summer precipitation was lower than average, the country faced severe localized flooding. In Geoje, rainfall reached 124.5 mm per hour, while southern regions and Jeju Island experienced significant droughts. By early September, weather patterns shifted toward significant temperature fluctuations and coastal warnings. Inland areas of the central and Gyeongsang provinces have seen daily temperature differences reaching approximately 15 °C. As of mid-September, daytime highs have reached up to 29 °C while morning lows have dropped to 11 °C, maintaining a daily gap of 10 to 15 degrees. Coastal warnings remain active due to strong winds and high waves, particularly around the Jeju coast and the East Sea, where waves may reach heights of 4 to 5 meters. Residents are advised to exercise caution regarding high swells. Furthermore, dry conditions in Seoul and western Gyeonggi provinces have prompted warnings for fire prevention. While air quality has remained at a ‘good’ level, morning fog in inland Gangwon and Jeonnam has previously reduced visibility to below 200 meters. ## Claims - Yangsan recorded a temperature of 42.5 °C, the highest in 122 years of observations. (disputed by 22 sources) - Yangsan recorded a temperature of 40.3 °C on 29 July 2026. (disputed by 5 sources) - Yangsan recorded a temperature of 39.9 °C on 29 July 2026. (disputed by 2 sources) - Three heat‑related deaths were reported in Gyeongsangnam‑do up to 28 July. (disputed by 2 sources) - Gyeongsangnam‑do recorded 112 heat‑related illness cases, including two deaths. (disputed) - President Lee Jae‑Myung called the heatwave a national disaster. (corroborated by 19 sources) - Since May 15, 2 025 people have suffered heat‑related illnesses nationwide. (corroborated by 19 sources) - The heatwave caused 19 deaths. (corroborated by 17 sources) - The Korea Meteorological Administration issued its first‑ever heat‑wave warning for parts of Seoul and later extended it to the whole capital. (corroborated by 17 sources) - The government provided temporary air‑conditioned housing for some residents affected by the heat. (corroborated by 14 sources) ## Timeline ### 2026-09-09: South Korea weather: Large temperature swings and strong coastal winds South Korea faces large daily temperature swings of up to 15 degrees, alongside strong winds and high waves along the coasts and Jeju Island. 4 sources. https://clstr.news/cluster/south-korea-weather-large-temperature-swings-and-strong-coastal-winds ### 2026-09-05: South Korea weather: Wide temperature swings and coastal wind warnings South Korea faces wide temperature fluctuations of up to 15 degrees, localized rain in Gangwon and Jeju, and strong winds and high waves along coastal areas. 2 sources. https://clstr.news/cluster/south-korea-weather-wide-temperature-swings-and-coastal-wind-warnings ### 2026-09-03: South Korea faces extreme summer heat and localized flooding South Korea faced extreme summer weather in 2026, including record heat of 42.5°C in Yangsan, intense localized flooding in Geoje, and significant droughts in southern regions. 3 sources. https://clstr.news/cluster/south-korea-faces-extreme-summer-heat-and-localized-flooding ### 2026-09-02: South Korea weather: Late summer heat and showers forecast South Korea faces late summer heat with perceived temperatures near 33°C in southern regions and Jeju, alongside forecasts for scattered showers and thunderstorms across various provinces. 3 sources. https://clstr.news/cluster/south-korea-weather-late-summer-heat-and-showers-forecast ### 2026-08-29: South Korea weather: Heavy rain and heat expected Heavy rain is forecasted across most of South Korea on August 31, with significant rainfall expected in the central regions and high perceived temperatures in the south and Jeju. 3 sources. https://clstr.news/cluster/south-korea-weather-heavy-rain-and-heat-expected ### 2026-08-25: South Korea weather forecast predicts heavy rain and showers South Korea faces heavy rain up to 80mm in southern regions and showers in the capital, offering slight relief from heatwaves despite high humidity and potential tropical nights. 2 sources. https://clstr.news/cluster/south-korea-weather-forecast-predicts-heavy-rain-and-showers ### 2026-08-24: South Korea faces continued heatwaves and thunderstorms South Korea continues to experience intense heatwaves and tropical nights despite the Cheoseo solar term, with localized thunderstorms and heavy showers expected in several regions. 3 sources. https://clstr.news/cluster/south-korea-faces-continued-heatwaves-and-thunderstorms ### 2026-08-21: South Korea faces heatwaves and heavy rain South Korea faces continued heatwaves with temperatures up to 35°C, heavy showers, and potential impacts from Typhoon Saudel as the traditional start of autumn arrives. 5 sources. https://clstr.news/cluster/south-korea-faces-heatwaves-and-heavy-rain ### 2026-08-18: South Korea faces heatwave and heavy showers South Korea faces continued heat with perceived temperatures near 33°C and widespread showers bringing up to 60mm of rain, thunderstorms, and potential landslide risks in southern regions. 2 sources. https://clstr.news/cluster/south-korea-faces-heatwave-and-heavy-showers ### 2026-08-12: South Korea weather: East Coast rain and heatwaves continue Rain is forecast for South Korea's East Coast with expected totals of 20–60mm, while heatwaves continue in the metropolitan and southern regions with perceived temperatures around 33°C. 2 sources. https://clstr.news/cluster/south-korea-weather-east-coast-rain-and-heatwaves-continue ### 2026-08-09: South Korea power demand nears record highs amid heatwave South Korea faces potential record-breaking electricity demand this week as heatwaves continue and industrial plants resume operations following summer breaks. 2 sources. https://clstr.news/cluster/south-korea-power-demand-nears-record-highs-amid-heatwave ### 2026-08-08: South Korea launches energy saving campaign amid heatwave South Korea is launching energy conservation campaigns and real-time billing alerts to combat rising electricity demand and costs driven by extreme heatwaves. 2 sources. https://clstr.news/cluster/south-korea-launches-energy-saving-campaign-amid-heatwave ### 2026-08-08: South Korea implements safety measures for heat wave South Korea is implementing emergency protocols and safety measures to protect migrant workers, elderly citizens, and livestock from extreme heat as heat-related illnesses continue to rise. 8 sources. https://clstr.news/cluster/south-korea-implements-emergency-heat-wave-protections ### 2026-08-07: South Korea mobilizes coast guard and agriculture ministry against heat‑wave health threats South Korea’s coast guard delivered ice water and safety advice to fishing vessels, while the agriculture minister inspected farms and greenhouses, urging heat‑illness precautions for workers amid a record heat 2 sources. https://clstr.news/cluster/south-korea-mobilizes-coast-guard-and-agriculture-ministry-against-heatwave-health-threats ### 2026-08-05: South Korea uses drones to warn farmers of extreme heat South Korea deploys drones in North Gyeongsang Province and Sejong City to broadcast heat‑wave warnings, deliver water and protect elderly farmers during a record‑breaking heatwave. 5 sources. https://clstr.news/cluster/sejong-city-deploys-drones-to-guard-farmers-against-heatwave-risks ### 2026-08-04: South Korea heatwave kills 21, declared national disaster South Korea’s August 2026 heatwave caused at least 21 deaths, over 2,000 heat‑related illnesses, a national disaster declaration, and a 39 °C forecast for Seoul. 41 sources. https://clstr.news/cluster/south-korea-president-lee-jaemyung-declares-heatwave-a-national-disaster-as-death-toll-reaches-19 ### 2026-08-03: South Korea faces record heat-driven power demand, activates emergency response South Korea's power grid faces record demand amid extreme heat, with forecasts up to 98.8 GW; authorities have activated emergency measures and maintain sufficient reserves. 2 sources. https://clstr.news/cluster/south-korea-faces-record-heat-driven-power-demand-activates-emergency-response ### 2026-08-02: South Korea ramps up heat‑wave safety measures for port and construction workers South Korea's Busan Port Authority and Public Procurement Service boost heat‑wave safety for port and construction workers, providing cooling supplies, rest breaks, and emergency inspections. 2 sources. https://clstr.news/cluster/south-korea-ramps-up-heatwave-safety-measures-for-port-and-construction-workers ### 2026-08-01: South Korea Deploys Citywide Cooling Shelters to Combat Extreme Heat South Korea is converting public spaces into a citywide cooling system, adding AI‑monitored shelters, canopies, fog and road‑spraying technologies to protect citizens from extreme heat. 2 sources. https://clstr.news/cluster/south-korea-deploys-citywide-cooling-shelters-to-combat-extreme-heat ### 2026-07-30: South Korea raises high‑temperature disaster alert to ‘Severe I’ for coastal fisheries South Korea’s Ministry of Oceans and Fisheries raised the high‑temperature disaster alert to level ‘Severe I’, issuing warnings for six sea areas and urging early harvest, emergency water discharge and other措施‑ 3 sources. https://clstr.news/cluster/south-korea-raises-hightemperature-disaster-alert-to-severe-i-for-coastal-fisheries ### 2026-07-28: Yangsan, South Korea hits 40.3°C as record‑breaking heatwave sweeps peninsula Yangsan hit 40.3 °C on July 29 2026, Busan 38.6 °C, as a double‑high‑pressure system drives a record heatwave across South Korea, prompting emergency warnings, drought alerts, three deaths and livestock losses, 10 sources. https://clstr.news/cluster/yangsan-south-korea-hits-399c-highest-temperature-in-122-years ### 2026-07-27: South Korea Elevates Heatwave Alert to Severe Level and Mobilises Disaster Headquarters South Korea raised the heat‑wave alert to Severe, activating a central disaster hub and prompting local districts like Gwangsan‑gu to roll out cooling shelters, health checks, and work‑site safety measures. 2 sources. https://clstr.news/cluster/south-korea-elevates-heatwave-alert-to-severe-level-and-mobilises-disaster-headquarters ### 2026-07-25: South Korea battles extreme heatwave as temperatures top 39°C and heat‑related illnesses rise South Korea endures a heatwave with temps over 39 °C, severe heat warnings, 1,200+ heat‑related illnesses and multiple deaths, urging precautionary measures. 6 sources. https://clstr.news/cluster/south-korea-issues-extreme-heat-warnings-as-heatwave-spikes-illnesses ### 2026-07-21: Imjin River flood warning issued as North Korean dam release raises water levels in Yeoncheon South Korea warned of flooding on the Imjin River in Yeoncheon after heavy rain and an unannounced release of water from North Korea’s Hwanggang Dam raised river levels to over 8 m, prompting evacuation alerts. 4 sources. https://clstr.news/cluster/south-korea-prepares-for-floods-as-north-korea-releases-water-from-hwanggang-dam ### 2026-07-19: Heavy Rain Forces Evacuation of Over 500 Residents in Central South Korea Heavy rain across central South Korea evacuated 557 people, caused 828 damage reports, but no deaths were recorded. 6 sources. https://clstr.news/cluster/south-koreas-economy-rises-on-semiconductor-export-surge-while-banks-tighten-loan-limits ### 2026-07-14: South Korea end‑June heatwave brings 33‑C temperatures, scattered showers and strong winds South Korea faced a 33‑C heatwave on June 15, with scattered showers, strong winds up to 90 km/h and tropical‑night temperatures, while air quality remained good. 2 sources. https://clstr.news/cluster/south-korea-endjune-heatwave-brings-33c-temperatures-scattered-showers-and-strong-winds ### 2026-07-12: South Korea issues inaugural emergency heatwave alert under new system South Korea issued its first emergency heatwave warning for Gyeongsan and Pohang, triggering nationwide health alerts, shelter operations and a surge in heat‑related illnesses as temperatures near 40 °C. 13 sources. https://clstr.news/cluster/south-korea-launches-first-extreme-heat-warning-for-pohang-and-gyeongsan ### 2026-07-10: South Korea issues first extreme‑heat warning for Gyeongsan and Pohang South Korea issued its first extreme‑heat warning for Gyeongsan and Pohang as temperatures topped 38 °C, prompting health alerts, outdoor‑activity bans and warnings for vulnerable groups. 7 sources. https://clstr.news/cluster/south-korea-endures-intense-heatwave-and-persistent-tropical-night ### 2026-07-09: South Korea braces for heavy monsoon rain and extreme heat as weekend dries up South Korea expects up to 200 mm of monsoon rain through July 10, followed by a heatwave with temps hitting 36‑37 °C and a second rain risk mid‑July. 2 sources. https://clstr.news/cluster/south-korea-faces-heavy-rain-followed-by-extreme-heatwave ### 2026-07-08: South Korea lifts nationwide heavy‑rain alert after days of flooding South Korea ends a national heavy‑rain alert after evacuating 758 people, reporting one death and over 450 facility damages, with widespread flooding and tree falls. 2 sources. https://clstr.news/cluster/south-korea-lifts-nationwide-heavyrain-alert-after-days-of-flooding ### 2026-07-07: South Korea braces for record heat and intense rainfall amid worsening climate trends South Korea could see up to a 6.2 °C rise in daily max temperature by 2100 under high emissions, while week‑long forecasts call for heavy rains up to 200 mm and temperatures up to 34 °C, heightening flood and “ 4 sources. https://clstr.news/cluster/south-korea-faces-heavy-rain-and-soaring-temperatures-as-summer-heat-intensifies ### 2026-07-04: South Korea grapples with heavy rain and heat wave June 6‑8 South Korea faces heavy rain and a heat wave from June 6‑8, with up to 100 mm of rain and temperatures above 30 °C, prompting flood and heat warnings. 6 sources. https://clstr.news/cluster/south-korea-sees-rain-and-heatwave-as-monsoon-begins ### 2026-06-27: South Korea heat wave brings scattered showers and temperatures above 30 °C South Korea faces a heat wave with temperatures up to 33 °C and scattered showers, thunderstorms and possible hail, prompting health warnings and advice to stay hydrated. 4 sources. https://clstr.news/cluster/south-korea-sees-widespread-30c-heat-and-sunny-skies ### 2026-06-24: South Korea experiences strong thunderstorms and heavy rain across central regions South Korea faces thunderstorms, gusty winds and heavy rain up to 30 mm/hr on June 26, with temperatures in the high 20s °C and good air quality. 2 sources. https://clstr.news/cluster/south-korea-experiences-strong-thunderstorms-and-heavy-rain-across-central-regions ### 2026-06-13: South Korea heatwave and strong showers sweep the nation on June 14‑15 South Korea faced a June heatwave with temperatures up to 32 °C and strong, localized showers, thunderstorms, and fog across many regions. 2 sources. https://clstr.news/cluster/south-korea-heatwave-and-strong-showers-sweep-the-nation-on-june-1415 ### 2026-06-13: South Korea faces 30°C heat with scattered showers on Saturday South Korea will experience nationwide 30 °C heat on Saturday, with highs up to 32 °C and afternoon showers in southern and inland regions, very high UV and moderate dust levels. 2 sources. https://clstr.news/cluster/south-korea-faces-30c-heat-with-scattered-showers-on-saturday --- Cite as: South Korea extreme summer weather: Heat, floods, and flux. CLSTR, https://clstr.news/situations/south-korea-heatwave-june-2026