As of the evening of June 13, 2025, much of South Korea is experiencing widespread rainfall, marking the early onset of the monsoon season. The Korea Meteorological Administration (KMA) reports that rain is currently falling across most regions, with southern Gyeonggi, Chungcheong, southern provinces, and Jeju Island particularly affected. This wet weather is set to expand through the night into the early morning of June 14, spreading across the metropolitan area and southern Gangwon before reaching the rest of the country.
The expected rainfall totals from June 13 to June 14 vary across regions, with Seoul, Incheon, Gyeonggi, and the West Sea 5 Islands seeing 5 to 40 millimeters. Southern Gangwon may receive 5 to 40 millimeters, while central and northern Gangwon expect 5 to 20 millimeters. The Chungcheong region is forecasted to see 10 to 60 millimeters, and northern North Chungcheong 5 to 40 millimeters. Southern provinces such as Gwangju and South Jeolla could experience 30 to 80 millimeters, with some coastal areas exceeding 120 millimeters. North Jeolla is expected to receive 20 to 80 millimeters, and Busan, Ulsan, and South Gyeongsang are looking at 30 to 80 millimeters, with some southern coastal areas and near Jirisan mountain receiving over 150 and 100 millimeters respectively. Daegu and North Gyeongsang will likely get 20 to 80 millimeters, while Ulleungdo and Dokdo islands may see 10 to 60 millimeters on June 14. Jeju Island stands out with an expected 50 to 120 millimeters, with mountainous areas potentially receiving over 250 millimeters.
The rain is forecast to taper off by the afternoon of June 14 across most of the country but will linger in Jeju until late that night. However, the wet pattern is not over; on June 15, rain will resume, beginning in Jeju in the morning, expanding to central regions and Jeolla provinces by afternoon, and reaching Gyeongsang in the evening. Rainfall on June 15 is expected to be lighter, ranging from 5 to 60 millimeters depending on the region.
Heavy downpours accompanied by thunder and lightning are anticipated from the night of June 13 through the morning of June 14, especially in Jeju Island, the southern coast, and areas near Jirisan mountain. These intense rainfalls could reach 30 to 50 millimeters per hour, prompting the KMA to warn of possible heavy rain advisories. Other southern regions and Chungcheong provinces may see strong rainfalls of 10 to 30 millimeters per hour during the same period.
The KMA has explained that a strong wind system, formed due to pressure differences, is transporting moisture-laden air from the tropics — a phenomenon known as the 'low-level jet.' When this humid air encounters mountainous terrain, such as Jeju's highlands and the southern coast, it results in significant rainfall due to topographical effects. This interaction is the primary cause of the heavy rain warnings issued for these areas.
Residents are advised to avoid riverside promenades and underpasses, as sudden flooding and rapid currents pose serious risks. Lowland flooding and river overflows are also concerns, especially with the anticipated heavy rain. The KMA urges caution in managing facilities and being vigilant about safety during thunderstorms and strong winds.
Temperatures during this period are expected to be near or slightly above average, with morning lows ranging from 15 to 23 degrees Celsius and daytime highs climbing to between 23 and 32 degrees Celsius. Notably, on June 14, temperatures will soar above 30 degrees Celsius mainly in the metropolitan area, while on June 15, the heat will spread to inland regions.
The monsoon season officially began early this year in Jeju Island on June 12, marking the third earliest start on record. Historically, the earliest monsoon starts in Jeju were on June 10 in 2011 and 2020, with June 12 in 1998 following closely. This early onset is linked to the passage of Typhoon Wutip, which formed near the Philippines on June 11 and moved northward along the coast of Vietnam before making landfall in southern China on June 14. As the typhoon dissipates, it releases substantial moisture that feeds into the monsoon system affecting the Korean Peninsula.
Typhoon Wutip, although not expected to directly impact South Korea, has influenced regional weather patterns. The typhoon's remnants are forecast to pass inland near Zhanjiang in China before weakening into a tropical depression north-northwest of Hong Kong by June 15. The moisture it leaves behind contributes to the ongoing rainfall and variability in precipitation areas until around June 16.
Looking ahead, the KMA forecasts that cold air masses will periodically move southward from the north between June 16 and June 21, interacting with the North Pacific High Pressure system, which will alternately expand and contract. This dynamic may lead to the formation of a stationary front in central regions around June 21, potentially marking the official start of the monsoon season in those areas. Interestingly, the southern provinces might not experience rain on that day, suggesting that the monsoon could begin earlier in the central parts of the country.
Throughout the weekend and into early next week, residents can expect humid and muggy conditions, with continuous rain in many regions. The KMA advises careful monitoring of weather updates, especially for those in vulnerable areas prone to flooding and landslides.
Maritime conditions are also challenging, with strong winds and high waves expected in the seas surrounding Jeju Island and southern coastal waters. Wave heights may reach up to 4 meters, and strong wind warnings are in place, particularly from the night of June 13 through June 14. Sea fog is another hazard, intermittently reducing visibility and posing risks for navigation and fishing activities. The KMA recommends that vessels operating in these waters exercise extreme caution and that sea travelers check updates before setting sail.
In summary, South Korea is entering a period of unsettled weather marked by heavy rains, strong winds, and rising temperatures. The early start of the monsoon in Jeju Island, influenced by the passage of Typhoon Wutip, signals a season that could bring both vital relief and significant challenges. Citizens are urged to stay informed and prepared as the weather continues to evolve over the coming days.
