Recent atmospheric conditions over the Korean Peninsula, marked by lingering high humidity and variable cloud cover from the East Asian monsoon transition, are driving substantial forecast uncertainty for Seoul-Incheon's overnight low on August 28. Multiple models show daytime highs near 29–30°C with scattered showers possible, but overnight radiative cooling rates will hinge on cloud thickness and wind patterns—clearer skies could allow lows to dip toward 23–24°C, while persistent overcast and light easterly flow may hold minima near 25–26°C. This narrow range around typical late-August climatology (historical averages near 22–24°C) explains the evenly matched market-implied probabilities across thresholds, as small shifts in precipitation timing or marine air influence from Incheon Bay can alter the exact minimum by 1–2°C. Updated KMA and ensemble guidance over the next 48 hours will likely narrow the spread ahead of resolution.