South Korea's Monsoon Season Likely to Start Late, Potentially by Two Weeks

South Korea faces a potential delay in the onset of its monsoon season, with current forecasts suggesting rain may begin on Jeju Island between June 30 and July 1, and reach the mainland around July 3. This timeline places the start significantly later than the average dates for Jeju (June 19), the southern region (June 23), and the central region (June 25).

Meanwhile, Japan is already experiencing its monsoon season, which began in early May in Okinawa and Amami and has since spread to Kyushu, Shikoku, and Tokai. While most of the Japanese archipelago is now under monsoon influence, some northern areas like Hokuriku and Tohoku have seen a delayed start compared to their average dates.

The delay in South Korea is attributed to the sluggish northward progression of the Pacific high-pressure system, which is crucial for pushing the monsoon front further north. If Jeju's monsoon officially begins on June 30-July 1, it would be more than 10 days later than average. A delay until early July would mean a lag of about two weeks, a situation not unprecedented, as seen in 2021 when the monsoon started on July 3 for all regions.

Despite the later start, forecasters caution that this does not necessarily mean less overall rainfall. Past experiences, such as in 2020, show that a delayed monsoon can still bring intense, concentrated downpours if the stationary front lingers over the Korean Peninsula for an extended period. The global forecast model indicates a potential rain band forming around July 3, but its exact location and intensity remain uncertain due to the forecast's 10-day horizon.