Recent Korea Meteorological Administration short-range forecasts project Seoul’s overnight minimum on May 18 near 14–15 °C under mostly clear skies and light winds, favoring radiative cooling that keeps the low in that narrow band. Ensemble guidance shows minor spread around these values, with slight differences in boundary-layer moisture and wind speed determining whether the reading settles at 14 °C or edges to 15 °C. Mid-May climatology for the city centers on 12–16 °C, providing context for why traders see the two leading outcomes as nearly equally likely and price them within two percentage points. New model runs and official updates over the next 48 hours will clarify any last adjustments to the forecast minimum.