Forecast models from the Korea Meteorological Administration and international ensembles indicate an overnight low of 23–25 °C for the Seoul-Incheon area on August 28, driven by persistent high humidity near 85–90 % and extensive cloud cover that limits nocturnal radiative cooling. Light easterly winds and a 30–60 % chance of showers further suppress temperature drops by enhancing downward longwave radiation and reducing clear-sky heat loss. Historical August climatology shows typical lows of 22–24 °C, but current conditions resemble recent days when minima held at 24–26 °C. Traders face genuine spread across the 22–26 °C bins because small shifts in cloud timing or boundary-layer moisture could push the official minimum one or two degrees either way before the Korea Meteorological Administration records the daily low at Incheon.