Heavy Rain Forecast for Jeju Island and Southern South Korea

Heavy rainfall is expected across South Korea tomorrow, March 18, 2026, with particularly intense precipitation forecast for Jeju Island and the southern coast due to the passage of a low-pressure system.

Rainfall Patterns

The rain will begin on Jeju Island and in the Honam region early tomorrow morning, expanding to cover most of the country throughout the morning. The precipitation is expected to subside in the western regions by late afternoon.

Precipitation Estimates

Mountainous areas of Jeju Island may receive up to 70mm or more of rainfall. The remainder of Jeju Island is predicted to experience between 30mm and 50mm of rain. Southern Jeollanam-do, the southern coast of Gyeongnam, and central Busan are expected to receive up to 30mm of precipitation. Central Gyeongsangbuk-do may spot between 5-10mm of rain.

Potential for Snow

Some high-altitude mountainous regions of Gangwon province may experience snowfall.

Atmospheric Conditions

Satellite imagery shows a low-pressure system currently approaching the southern part of the West Sea. This system will impact the country tomorrow, bringing widespread cloud cover. While the southern region will experience heavy rain that will help clear dust, air quality in the central region will remain cloudy.

Temperature Outlook

Morning temperatures will be relatively mild, with Seoul reaching 6 degrees Celsius due to warm air flowing in ahead of the low-pressure system. However, daytime highs will drop to 11 degrees Celsius in Seoul and 13 degrees Celsius in Gwangju, representing a decrease of approximately 5 degrees Celsius compared to today. Clear weather is anticipated following the passage of the rain.

Spring Weather Conditions

The weather will be chilly in the mornings and warmer during the day, typical of early spring conditions.

(Nam Yu-jin, SBS Weather Caster)