Recent forecast models, including GFS runs, indicate a highest temperature near 22–23°C for Istanbul on September 13, driven by northerly winds, increasing cloud cover, and a modest chance of light showers that limit daytime heating. These conditions align with seasonal norms of roughly 23–24°C while introducing modest cooling from partial cloudiness and elevated humidity near 70%. Trader consensus, reflected in the 56.5% implied probability for 22°C and 27.5% for 23°C, incorporates remaining uncertainty in model timing of any precipitation and exact wind speeds, with lower probabilities assigned to warmer or cooler extremes. Updated model guidance and official observations tomorrow morning will refine the final maximum reading used for market resolution.