Recent forecast model runs from the Korea Meteorological Administration and international sources such as the Met Office and NOAA-aligned guidance indicate overnight lows in Seoul-Incheon of 17–19 °C on September 26, with the tightest clustering around 18–19 °C under partly cloudy skies after early rain clears. Persistent cloud cover and light easterly winds from the preceding frontal system have limited radiational cooling, keeping minimum temperatures above seasonal norms near 17 °C. This consensus, combined with stable high pressure building from the west, underpins the market’s heavy weighting toward 19 °C as the recorded low, while residual model spread leaves modest probability on 18 °C or 20 °C. Updated guidance expected overnight will refine the final range before observations close the market.