Recent forecasts from the Korea Meteorological Administration and models indicate overnight lows in Seoul around 18–20°C for June 21, driven by increasing cloud cover and the early influence of the East Asian monsoon, which moderates diurnal temperature ranges through higher humidity and reduced radiative cooling. Typical June climatology shows average morning lows near 17–19°C, with variability tied to steering patterns, wind direction, and any overnight precipitation that prevents sharp drops. Trader sentiment clusters on 19–20°C outcomes because current model runs align closely with these baselines while highlighting uncertainty from potential timing shifts in frontal systems or clearer skies that could push the minimum slightly lower or higher.