Recent forecast guidance for Incheon and Seoul points to overnight lows near 19–20°C on September 25 amid widespread cloud cover and a 50–85% chance of rain, keeping minimum temperatures elevated through reduced radiative cooling and higher humidity. These conditions align with the market’s tight clustering around 19°C (29.5%) and 20°C (23.5%), while the notable share for 15°C or below reflects residual model uncertainty over exact timing of showers and wind shifts that could allow brief clearer periods. September climatology shows typical minima of 18–20°C, and the current setup favors moderation rather than sharp drops. Updated model runs and official Korean Meteorological Administration guidance in the next 24–48 hours will likely clarify whether the low settles at or above 19°C.