South Korea braces for frosty mornings, mild afternoons; frost risk and rough seas.

South Korea is forecast to experience mild, seasonal temperatures over the weekend, with a notable difference between morning and afternoon temperatures in many areas. Inland, morning temperatures are expected to fall to around or below 0°C, while daytime highs range from about 10° to 15°C.

Frost is possible in parts of the inland Chungcheong region and southern inland areas, so farmers should monitor crops and take precautions against freezing overnight. The general pattern through Sunday is for mornings to stay near or below freezing and afternoons to rise into the low to mid-teens.

Major cities look to see a range of daytime highs: Seoul, Suwon and Ulsan around 12°C; Incheon about 10°C; Gangneung, Sejong, Busan and Jeju near 13°C; Daejeon about 14°C; and Gwangju and Daegu near 15°C. Sunday should mirror the pattern, with similar temperatures and a continuing large diurnal swing.

Cloud cover will be mixed. The central region is likely to be mostly cloudy, with the southern regions sometimes broke up by clouds; Jeju Island should be generally clearer. Inland areas can experience fog in the morning, with visibility under 1 kilometer in some places, and fog could be denser along rivers and valleys. Drivers and water users are advised to exercise caution where visibility is reduced.

Offshore winds will be strong in several zones, with gusts between 30 and 60 kilometers per hour reported in the East Sea’s southern outer waters, the South Sea’s eastern outer waters, and the Jeju region’s southeastern inner waters; winds along Jeju’s southern outer sea may persist into the afternoon. Expect rough seas and swells along the east coast and around Jeju, which could affect shipping, fishing, and port operations.

Fine dust levels across the country are forecast to be in the good to moderate range, a positive note for outdoor activity and health advisories. Air quality remains a common consideration for outdoor events, commuting, and industrial activity in Korea.

Why this matters to U.S. readers: South Korea is a major supplier of electronics components and other manufactured goods that feed into global supply chains, including those reaching American markets. Weekend weather and offshore wind conditions can influence shipping schedules, port congestion, and logistics around Busan and Incheon, potentially affecting deliveries to the United States. Frost risk and fog can impact agricultural inputs and cross-border trade in sensitive commodities. Finally, Korea’s weather and air quality data feed into broader regional environmental monitoring and energy use patterns, relevant for U.S. policymakers and markets tracking East Asian supply chains, security corridors, and climate policy.