Forecast models and official guidance from agencies tracking the region indicate a high near 25°C for Seoul and Incheon on September 26, driven by increasing cloud cover, light easterly winds, and residual moisture from overnight rain that limits daytime heating. Seasonal transition into autumn further moderates temperatures below late-summer peaks, with consensus across runs clustering between 24–26°C. Market-implied odds, led by 25°C at 51.5% followed by 26°C and 24°C, reflect traders weighting this narrow forecast range while accounting for minor model spread and potential microclimate differences between Seoul and Incheon stations. Final resolution will hinge on verified maximum observations once the day concludes.