Recent ensemble forecasts from the Korea Meteorological Administration indicate overnight lows in Seoul on June 19 most likely settling between 19–20 °C, driven by typical early-summer radiative cooling under partly cloudy skies and light winds. Higher dew points associated with rising humidity limit the temperature drop after sunset, while any increase in cloud cover or wind would further suppress minimum readings by reducing net longwave heat loss. Model spread remains modest at this short lead time, reflecting uncertainty in exact timing of any weak frontal passage or localized showers that could alter nocturnal boundary-layer stability. Historical climatology for mid-June places average lows near 18–19 °C, providing context for why traders assign the highest implied probabilities to the narrow 19–20 °C band ahead of updated model runs expected within the next 24 hours.