Recent forecasts for Incheon and Seoul on September 23 indicate mostly clear skies and light winds under stable high pressure, supporting radiative cooling overnight with consensus lows near 19–20 °C. These conditions align with the late-summer transition, where moderating Pacific air and reduced humidity allow temperatures to fall more readily after sunset compared with peak monsoon periods. Minor model spreads in timing of any thin cloud cover or subtle wind shifts create the tight clustering around 19 °C and 20 °C in trader pricing, while lower probabilities for 17 °C or below reflect limited cold-air advection potential and historical September baselines that rarely dip that far without stronger frontal influence. Updated runs from global models over the next 48 hours will likely refine the exact minimum before resolution.