Current forecasts from meteorological models and real-time observations across Seoul and Incheon stations show overnight lows stabilizing near 20°C under mostly cloudy conditions with light westerly winds and high humidity, supporting the market's strong 98.6% implied probability for that exact minimum. This aligns with typical mid-September climatology for the region, where diurnal ranges narrow as seasonal cooling begins but without significant cold air advection. A realistic challenge could arise from localized radiative cooling under clearer skies or revisions in official station data, though model consensus and recent hourly readings indicate low likelihood of dropping to 19°C or below before midnight.