Recent forecasts from the Korea Meteorological Administration indicate Seoul will experience a mild late-spring day on May 18 under clear skies and light southwesterly flow, with daytime boundary-layer heating expected to push the official maximum to 25°C or higher. This outlook aligns with mid-May climatology at 37.5°N, where average highs range 23–26°C amid lengthening daylight and the seasonal retreat of cooler northerly air masses. Ensemble guidance shows modest spread around the central value, with warmer solutions tied to stronger mixing and slight cooling possible only if cloud cover increases or winds shift earlier than modeled. Traders are weighting these variables against the narrow resolution window for the Incheon station reading, sustaining the strong market-implied probability for the upper outcome while leaving limited room for downward revision absent a significant forecast shift.