Official forecasts from the Korea Meteorological Administration indicate a maximum of 29°C for Seoul and Incheon on August 21, with cloudy conditions and a 60% chance of afternoon rain. This drives the tight clustering of market-implied odds around 28–30°C, as precipitation and increased cloud cover limit solar insolation and surface heating compared to clearer days. Late-August climatology shows a seasonal decline in daily highs from peak summer values near 31–33°C, with higher humidity and potential monsoon remnants further moderating temperatures. Updated model runs and the proximity to resolution heighten sensitivity to any shifts in steering patterns or rainfall timing that could alter the peak by 1–2°C.