Recent Korea Meteorological Administration forecasts highlight a southerly flow advecting warmer, moist air across the Korean Peninsula, positioning Seoul’s daytime maximum near or above 25°C for May 18 under mostly clear skies and typical late-spring insolation at 37.5°N latitude. Ensemble guidance from the European Centre for Medium-Range Weather Forecasts shows limited spread, with stronger boundary-layer mixing favoring slight additional warming while modest cloud increases or a wind shift could cap readings at 24°C. This aligns with mid-May climatology where historical highs average 19–23°C yet frequently exceed 25°C during warm-advection episodes. Traders are weighting these model consensus signals and the narrow resolution window for the official observatory reading, which sustains the 80.5% market-implied probability for 25°C or higher.