Forecast models from agencies including the Korea Meteorological Administration indicate a minimum temperature near 21–22°C for Incheon on August 12, 2026, reflecting the primary driver of current market pricing. Persistent summer humidity and limited nocturnal radiative cooling under partly cloudy conditions typically constrain overnight drops in the Seoul metropolitan area, where the urban heat island effect adds roughly 1–2°C relative to rural baselines. Recent heatwave conditions with daytime maxima near 34–36°C have maintained elevated soil and boundary-layer warmth, narrowing the expected diurnal range. Ensemble variability between 21°C and 22°C outcomes stems from small differences in projected wind speeds and cloud timing, creating the tight 34%–32.5% split between those bins while lower probabilities attach to cooler or warmer extremes. Updated model runs and official guidance within the next 48 hours will likely refine this range ahead of market resolution.