Current Korea Meteorological Administration guidance centers the daytime high for Busan on May 18 around 28–30°C, driven by a strengthening high-pressure ridge and southerly flow that advects warmer maritime air while limiting cloud cover. This synoptic setup favors modest daytime warming over the coastal station, where sea-breeze moderation typically caps peaks near the upper end of seasonal norms. Market-implied odds cluster tightly between the 29°C and 30°C brackets because short-range ensemble runs show only small differences in afternoon insolation and wind timing that could shift the precise maximum by 1–2°C. Traders monitor the next KMA model update for any revisions in boundary-layer mixing or ridge positioning before the daily peak is recorded.