Recent forecasts for Incheon and Seoul on September 28 show daily minimum temperatures clustering near 16–20 °C, with model spread creating the tight market distribution. Clearer skies and northwesterly flow in some ECMWF and GFS runs support radiative cooling toward the mid-teens, while increased cloud cover and lighter winds in others limit overnight drops near 19 °C. Current conditions feature mild autumn air masses with highs around 24–26 °C and modest humidity, typical for late September climatology. Resolution hinges on official KMA observations at the Incheon station, where even small shifts in nocturnal boundary-layer mixing or residual moisture can alter the recorded minimum by 2–3 °C. Traders are therefore weighting the balance between cooler clear-night scenarios and warmer, cloudier outcomes as new model runs arrive.