The Jeju Regional Meteorological Administration announced the start of the monsoon season on July 30, 2024 [1].
The delayed onset of the rainy season disrupts typical weather patterns for the South Korean island, bringing an immediate risk of flash flooding and wind damage.
Forecasters expect heavy rain from the early hours of July 1 through the early hours of July 2, 2024 [1]. The weather system is driven by a north-Pacific high-pressure system and a stationary front moving north, which are funneling moisture toward the region [1].
Local authorities have issued heavy-rain and strong-wind advisories. The administration said that some areas may experience intense rainfall of approximately 30 mm per hour [1]. This precipitation is expected to be accompanied by gusty winds and thunderstorms, particularly between the early hours and morning of July 1 [1].
Expected rainfall totals vary by geography. Non-northern areas of Jeju are forecast to receive between 50 and 100 mm of rain [1]. However, mountainous regions and the mid-mountain zone of Seogwipo could see totals of 180 mm or more [1].
This year's start date is historically unusual. The July 30 start marks the third latest monsoon beginning since records began in 1973 [2]. For comparison, the latest start on record occurred on July 7, 1982 [2], and the second-latest occurred on July 3, 2021 [2].
Officials are monitoring the stationary front as it continues its northward movement. The Jeju Regional Meteorological Administration said the weather will remain volatile as the system passes through the region [1].
“This year's start date is historically unusual.”
The extreme delay in the 2024 monsoon start suggests significant shifts in regional atmospheric pressure and moisture transport. When a season begins this late, the resulting precipitation often arrives in more concentrated, violent bursts rather than steady rain, increasing the risk of landslides in Jeju's mountainous terrain and infrastructure damage in coastal zones.
