Heavy Rains And Heat Grip South Korea Nationwide

On September 20, 2025, South Korea found itself in the grip of relentless late-summer heat and bouts of heavy rainfall, as much of the country experienced a challenging mix of sultry temperatures and intermittent downpours. According to multiple reports from local outlets including Daily Hankook, Money Today, and Asia Times, the third Saturday of September brought widespread cloud cover and significant precipitation, with meteorologists urging caution as thunderstorms and sudden showers swept across the peninsula.

From the early hours, the Korea Meteorological Administration (KMA) had warned that the day would bring not only overcast skies but also bursts of rain, some of it intense enough to prompt safety advisories. Rainfall was forecast to be particularly heavy in regions like Chungnam’s west coast and Jeonbuk, where expected precipitation ranged from 30 to 80 millimeters. Other areas, including Incheon, southern Gyeonggi, the five West Sea islands, parts of Gangwon, Chungcheong, Gwangju, Jeonnam, Daegu, and Gyeongbuk, were predicted to see between 20 and 60 millimeters of rain. Even Seoul, northern Gyeonggi, and northern Gangwon were not spared, with estimates of 10 to 40 millimeters.

Yet, the rain was only part of the story. Temperatures across the nation remained stubbornly high, refusing to offer the kind of relief many hoped the showers would bring. The KMA noted that morning lows spanned from 16°C to 26°C, with Seoul waking up to 18°C, Chuncheon at 16°C, Gangneung at 17°C, Daegu at 19°C, Jeonju at 21°C, Busan at 24°C, and Jeju at a balmy 26°C. As the day progressed, heat built up further, with afternoon highs ranging from 23°C to 29°C. Notably, Seoul reached 24°C, Gangneung 23°C, Gwangju 26°C, Daegu 27°C, Jeju 28°C, and Busan peaking at 29°C. These figures, as Money Today pointed out, were somewhat above seasonal averages, marking the day as warmer than usual for this time of year.

The heat wasn’t just an urban inconvenience. Central regions, particularly the west coast of Chungnam and Jeonbuk, saw the highest temperatures, with some forecasts initially reporting a range of 30°C to 80°C—a clear typographical error, but one that underscored the perception of oppressive heat. More accurate readings placed the upper end of daily highs closer to 38°C in the hottest spots. Elsewhere, regions such as Incheon, southern Gyeonggi, and the five West Sea islands experienced highs between 20°C and 60°C, while Seoul and northern Gyeonggi saw the mercury climb to between 10°C and 40°C. Gangwon’s Yeongseo and Yeongdong areas, along with Chungcheong, Gyeongju, Jeonnam, Daegu, and Gyeongbuk, also recorded temperatures within the 20°C to 60°C band.

Adding to the day’s complexity was the humidity, which, when combined with the heat, created a muggy atmosphere that many residents found draining. The KMA highlighted that the heat wave was persisting, especially in the central regions, and that the combination of high temperatures and humidity would likely continue to make conditions uncomfortable. The agency also noted that Gangwon’s Yeongdong area could expect these hot and humid conditions to last until at least September 21.

Despite the challenging weather, there was a silver lining for those concerned about air quality. Thanks to the widespread rainfall and efficient atmospheric circulation, fine dust concentrations were expected to remain in the “good” category across all regions, according to Money Today. This offered a small measure of comfort for residents, especially those with respiratory issues, who could at least breathe a little easier amid the heat and rain.

Maritime conditions were also under close observation. The KMA reported that wave heights would vary by region, with the east coast’s nearshore waters seeing waves from 0.5 to 3.5 meters, the west coast from 0.5 to 2.0 meters, and the south coast from 0.5 to 1.5 meters during the day. At night, offshore waves were expected to reach 1.5 to 3.5 meters in the west, 1.0 to 3.5 meters in the east, and 0.5 to 2.0 meters in the south. These fluctuations prompted authorities to advise caution for fishermen and those involved in maritime activities.

The rain, while providing some respite from the heat, brought its own hazards. The KMA cautioned that in areas experiencing heavy downpours, visibility could drop quickly, and roads might become slippery or even flooded. “Drivers should pay extra attention to traffic safety, as sudden rain can sharply reduce visibility and make roads treacherous,” the agency advised, as reported by Asia Times. For those living in or traveling through regions prone to flash floods or landslides, the risk was even higher, especially with thunderstorms and lightning in the forecast.

As is often the case with Korea’s late summer weather, the pattern of rain and heat was not uniform across the country. While most regions saw the rain taper off by midday, the east coast of Gyeongbuk and Gangwon’s Yeongdong area were expected to continue receiving rain into the night and possibly through the following day. This patchwork of conditions meant that while some residents could put away their umbrellas by afternoon, others had to remain vigilant for longer.

In the midst of the weather coverage, local media slipped in practical advice for daily living. For example, Asia Times offered a household tip: “Eggs, milk, and potatoes shouldn’t be kept in the freezer. Eggs can crack and let in bacteria, while milk separates into fat and water.” It was a gentle reminder that even when the weather dominates headlines, the small details of everyday life matter, too.

Looking back, the weather on September 20, 2025, served as a microcosm of the country’s late summer climate—unpredictable, at times extreme, and always demanding attention. With meteorologists continuing to monitor conditions and issue advisories, residents were reminded of the importance of staying informed and prepared, whether facing heat, rain, or the occasional thunderstorm. For now, South Korea’s battle with the elements continues, with everyone hoping for a break in the heat and clearer skies ahead.