**Persistent midsummer warmth under a high-pressure ridge is anchoring the lowest temperature in Incheon on August 4 near 27°C.** Official Korea Meteorological Administration short-range guidance and global ensemble models project overnight minima of 26–28°C, consistent with typical early-August climatology for the region where average lows hover around 23–25°C but elevated humidity and light winds limit radiational cooling. Incheon’s coastal location provides modest moderation relative to inland Seoul, keeping extremes from deviating sharply. Recent observations show no significant frontal passages or typhoon influences through the period, supporting the market’s heavy weighting toward 27°C (52%) and 28°C (27.5%) outcomes. Updated model runs and KMA briefings over the next 48 hours remain the key variables that could shift implied probabilities if a cooler air mass arrives earlier than currently expected.