Widespread Rain Ushers In Autumn Across Korea

As South Korea marks the autumnal equinox on September 23, 2025, the country finds itself bracing for a classic seasonal weather shift: widespread rain, cooler evenings, and a few surprises from the skies. According to the Korea Meteorological Administration (KMA), a frontal system drifting eastward from northern North Korea towards northeastern China is set to drape the peninsula in clouds and periodic showers, bringing relief from the persistent summer heat and ushering in the first true taste of fall.

From the early hours, residents of Jeju Island will be the first to hear the pitter-patter of rain, with precipitation expected to begin between 9:00 and noon, as reported by Headline Jeju. By evening, the rain will have reached the southern coastal regions, stretching inland and intensifying overnight. The KMA forecasts rainfall amounts between 10 and 40 millimeters for Jeju and the southern provinces, with slightly less—around 5 to 20 millimeters—specifically predicted for Jeju Island. The pattern is clear: the rain starts in the south and works its way north, blanketing much of the country by the following day.

But it’s not just the rain that’s getting attention. The temperature swings are worth noting, too. The morning lows will range from a brisk 13 to 21 degrees Celsius, depending on the region, while afternoon highs will hover between 23 and 29 degrees Celsius. In Seoul, for instance, the day will start at a cool 18 degrees before climbing to a comfortable 27 degrees, according to Public Times. Inland areas could see even more dramatic fluctuations, with the KMA warning that the difference between day and night temperatures may reach up to 20 degrees in some places. That’s a recipe for chilly evenings, so health officials are urging people to dress in layers and keep an eye on vulnerable family members.

For those planning to head outdoors, especially hikers eyeing the scenic trails of Deogyusan National Park, the advice is clear: pack for rain and cooler temperatures. Point Daily reports that the mountain will remain overcast all day, with temperatures peaking at just 17 degrees Celsius in the afternoon and humidity hovering around 70 to 90 percent. Winds will be steady from the east and southeast, reaching up to 5 meters per second. With the risk of damp, cold conditions, hikers are urged to bring warm, windproof clothing and to be mindful of slippery paths as evening falls.

Meanwhile, coastal areas—particularly Jeju Island—are bracing for more than just rain. The KMA has issued warnings for strong winds, with gusts on Jeju’s coast expected to reach 15 meters per second and even up to 20 meters per second in higher elevations. Tidal waves off Jeju’s southern coast will rise to between 2.0 and 3.5 meters, while the west and south coasts can expect waves of around 1.5 meters, as detailed in Asia Economy. Mariners and fishermen are being advised to exercise caution, and coastal authorities are keeping a close watch on conditions.

Despite the unsettled weather, there’s a silver lining for air quality. Thanks to steady air movement and the cleansing effect of the rain, fine dust concentrations will remain at “good” levels nationwide, according to both Asia Economy and Public Times. That’s a welcome respite for those with respiratory issues, especially after a long, hot summer marked by occasional pollution spikes.

Looking ahead, the rain won’t be a one-day affair. By September 24, the KMA expects precipitation to intensify and expand northward, covering the entire country. Central and northern regions—including the capital area and Gangwon Province—could see rainfall totals jump to between 20 and 60 millimeters, while the south continues to receive 10 to 40 millimeters. News1 notes that Gangwon’s Gangneung area, which already saw a 60-millimeter downpour on September 20, should be prepared for more wet and windy weather as the front moves through. Residents and local officials are being urged to stay vigilant, monitor forecasts, and take precautions to prevent water damage and accidents.

As for the broader meteorological picture, the KMA is keeping an eye on the Western Pacific, where Typhoon Lagasa (the 18th of the season) and Typhoon Neoguri (the 19th) are both on the move. Fortunately, current models predict that neither storm will directly impact Korea. Lagasa is headed toward China’s Jiangxi province, while Neoguri is steering well southeast of Japan, according to Headline Jeju. That’s a relief for a region often battered by late-summer typhoons, though officials caution that the situation could change and urge continued vigilance.

For those wondering about the weekend and the week ahead, the forecast offers a mix of clouds, intermittent rain, and the occasional sunny spell. The KMA predicts that rain will linger into September 25, with the heaviest downpours expected in the early hours for northern regions, gradually tapering off from north to south. By Friday, the skies should begin to clear over the capital and northeastern areas, with most of the country enjoying drier, slightly warmer weather by the weekend. Daytime highs will settle in the mid to upper 20s, and nighttime lows will dip into the low teens in some inland areas—a classic early autumn pattern.

As always, the meteorological office is urging the public to heed weather advisories, especially regarding sudden gusts, thunder, and lightning. "In areas where rain falls, there may be gusty winds, thunder, and lightning," a KMA spokesperson told Asia Economy. "Please be cautious with facility management and safety accidents." The agency also warns that visibility could be reduced on wet roads, increasing the risk of traffic accidents, and that sudden weather shifts may catch some unprepared.

In summary, South Korea’s transition from summer to autumn is arriving right on schedule, bringing with it the hallmarks of the season: rain, cooler nights, and the promise of crisp, clear days ahead. While the weather may put a damper on some outdoor plans, it’s also a welcome sign that the relentless heat is finally giving way—and that autumn’s embrace is just around the corner.