Latest meteorological model consensus, including GFS runs, projects a maximum temperature near 22°C for Istanbul on September 26 under partly cloudy skies with persistent northeasterly winds around 20-25 km/h limiting daytime warming. This aligns with seasonal norms for late September while reflecting current atmospheric conditions that suppress stronger heating. Traders appear to weight these stable forecasts heavily, concentrating implied probabilities on 21-23°C outcomes, though minor model variations in cloud cover or wind strength could shift the exact peak. Official observations from the Turkish State Meteorological Service will determine the final high.