Official Korea Meteorological Administration guidance forecasts a 24°C morning minimum for August 18 in the Seoul-Incheon area under mostly cloudy early conditions clearing later, with light winds and low precipitation chances supporting modest overnight radiative cooling. Ensemble model spreads produce closely matched probabilities for 23–25°C, driven by small differences in predicted cloud timing, boundary-layer moisture, and surface wind that control heat retention near the ground. Historical August climatology shows typical lows near 23–24°C, and the current pattern lacks strong frontal passages or unusual humidity anomalies that would sharply deviate from this range. Traders therefore assign the highest implied probability to 24°C while pricing modest tail risk for slightly cooler or warmer realizations pending the final observational window.