Recent ensemble forecasts from Météo-France and other models indicate overnight lows in Paris clustering around 17–19°C on August 18, following a mid-August heatwave and subsequent cooling trend driven by Atlantic air advection under partly cloudy skies. Trader sentiment remains tightly balanced because small differences in cloud cover, wind speed, and radiative cooling rates—key controls on minimum temperature—can shift outcomes by 1–2°C. Historical late-summer climatology supports this narrow range, with limited radiative cooling expected in an urban setting. Updated model runs and official guidance over the next 48 hours will likely refine these probabilities ahead of market resolution.