Traders are weighting 28–29°C most heavily for Seoul’s June 15 daily maximum because short-range guidance from the Korea Meteorological Administration and global ensembles currently favors a peak near 28–29 °C under building high pressure and modest southwest flow. Afternoon humidity around 50–60 % and scattered cloud or light shower chances introduce modest uncertainty in the exact maximum, while the urban heat-island effect and longer daylight favor slight upward bias. A 30 °C outcome would require stronger insolation and drier boundary-layer air than most runs indicate, whereas 27 °C or lower would need more persistent cloud or a timing shift in the ridge. Updated model cycles tomorrow morning and any revised KMA guidance will be the next key catalysts for shifts in these closely matched probabilities.