Latest short-range forecasts from the Korea Meteorological Administration project Seoul’s May 17 afternoon maximum near 24–25 °C, sustaining the near-equal 27.5 % market shares on those two bins. A weakening high-pressure ridge allows modest southerly warm-air advection while increasing mid-level moisture promotes afternoon cloud cover that caps surface heating. Small model differences in the timing of boundary-layer mixing and localized urban-heat amplification create the tight spread between 24 °C and 25 °C, whereas the 19 % on 26 °C or higher reflects the modest upside risk if skies clear earlier than expected. Historical May climatology places the typical daily high near 22–23 °C, so current guidance sits modestly above average. The next KMA update and morning radiosonde data will narrow the remaining uncertainty before resolution.