Clear skies and light northerly winds are driving moderate overnight radiative cooling across the Seoul-Incheon region, with official forecasts from agencies like the Korea Meteorological Administration pointing to a daily minimum near 19–20°C under stable high-pressure conditions. This aligns closely with the market’s leading implied probabilities, as September climatology typically features lows of 15–18°C but current dry air and limited cloud cover limit deeper drops. Model consensus shows minimal precipitation risk and steady northwest flow preventing significant cold advection, while historical analogs for mid-September under similar setups rarely dip below 18°C. Final Incheon station observations will resolve the market once the full 24-hour period ends.