As South Korea awoke on May 20, 2026, commuters across the nation were greeted by a relentless downpour and blustery winds, signaling a dramatic shift from the early summer heat that had gripped the country in recent days. According to YTN, rain clouds blanketed the entire country during the morning rush hour, with umbrellas becoming an essential accessory for anyone heading outdoors. The sudden return of wet, windy weather brought not only inconvenience but also a much-needed break from the unseasonable warmth, as temperatures took a notable plunge.
In Seoul, the daytime high was forecast to reach just 20 degrees Celsius, a drop of more than 5 degrees compared to the previous day. The pattern was echoed across other major cities: Daejeon braced for a high of 19°C, while Daegu was expected to remain at a cool 18°C, as reported by Yonhap News TV. The chill was felt even more acutely in southern cities, where Busan’s mercury was set to top out at 21°C, and Gimhae and Miryang hovered around 20°C, according to KNN.
But the real story was the rain—and there was plenty of it. The Korea Meteorological Administration issued heavy rain advisories for several regions, most notably the mountainous areas of Jeju, where rainfall rates of about 10mm per hour were measured early in the day. By late afternoon, the central west coast, Yeongdong, and Jeju’s mountains were expected to be drenched by torrential spring storms, with total accumulations forecast to exceed 100 to 150mm by the afternoon of May 21. In Gangwon’s mountainous zones, the numbers could climb even higher, reaching up to 150mm, while Jeju’s peaks were bracing for up to 120mm, according to detailed forecasts from Yonhap News TV.
The deluge wasn’t limited to just those areas. The southern coast of Gyeongnam prepared for more than 80mm of rain, with KNN warning that the heaviest bursts—up to 20mm per hour—would likely strike between late night on May 20 and the early morning hours of May 21. Busan and other parts of Gyeongnam were forecast to see 20 to 60mm of rainfall, while inland regions such as Jinju and Hapcheon expected daytime highs of only 19°C, making for a noticeably brisk day after the recent heat spell.
The central regions and southern coastlines, meanwhile, were placed on alert for the most intense downpours, with News1 reporting that rain could fall at rates of 20 to 30mm per hour. This meant not just inconvenience but also heightened risks, as thunder, lightning, and sudden gusts of wind swept through. The Jeonbuk region, according to Jeonbuk’s Voice, was forecast for 20 to 60mm of rain, with strong winds and high sea waves adding to the hazards—especially for those living or working near the coast. Sea levels were noted to be higher than usual, prompting additional warnings for possible flooding in low-lying coastal areas.
Wind was another major player in this weather drama. As reported by Yonhap News TV, wind advisories were issued for Jeollanam-do’s Heuksando and Hongdo islands, where gusts were expected to reach 15 to 20 meters per second. By afternoon, these powerful winds were forecast to sweep across the entire country, raising concerns about the safety of outdoor structures and the risk of accidents. Residents were urged to secure loose items and exercise caution when venturing outside. "Facilities management and safety precautions are necessary," the weathercaster emphasized on Yonhap News TV, highlighting the potential for damage and disruption.
The weather wasn’t just a matter of inconvenience—it also brought a dramatic drop in temperatures. In some areas, the mercury was projected to fall by as much as 10 or even 11 degrees compared to the previous day. Morning lows across the country ranged from 15 to 19°C, with Busan starting the day at 18°C and Changwon at 17°C, as KNN detailed. This sudden cool-down was welcomed by many, offering a respite from the early heat, but it also meant that people needed to dig out their jackets and raincoats once more. "The heat that continued recently will subside as the rain cools things down," KNN’s morning weather segment reassured viewers.
For those keeping an eye on air quality, there was some good news: fine dust and ultrafine dust levels remained at ‘good’ or ‘normal’ levels, according to Jeonbuk’s Voice. This was a small comfort amid the otherwise wet and windy conditions. The waves on the southern and northern West Sea were forecast to reach heights of 0.5 to 1.5 meters, adding to the marine warnings for fishermen and coastal residents alike.
Despite the severity of the storm, there was light at the end of the tunnel. Meteorologists across all networks agreed that the rain would begin to taper off by the afternoon of May 21. Afterward, the skies were expected to clear, with a return to warmer-than-usual weather likely as the weekend approached. However, KNN cautioned that daytime temperatures would remain below average until Saturday, May 23, giving South Koreans a few more days of cool relief before the heat returned.
Yet, the intensity of the rain brought its own set of dangers. YTN warned that rivers could rise rapidly due to the heavy downpours, raising the risk of sudden flooding and safety accidents. Coastal areas, particularly those at low elevations, were also at risk of flooding due to higher-than-normal sea levels. The message was clear: keep an umbrella handy, dress in layers, and stay alert for changing conditions.
Amidst all this, the country’s meteorological services continued to monitor the situation closely, with advisories and updates broadcast throughout the day. From the capital to the southernmost islands, the consensus was to take the weather seriously. "Strong rain and wind will continue throughout the day, with daytime temperatures remaining cool," the weathercaster on Yonhap News TV summarized, urging the public to prioritize safety.
As South Korea endures this bout of spring storms, the collective hope is that the rain will bring not just cooler temperatures but also a fresh, clean start before summer’s heat inevitably returns. For now, though, it’s umbrellas up and eyes on the sky.