**Trader consensus heavily favors 19°C as the day's official high in Istanbul, with 92.7% implied probability.** This positioning reflects current observations and model guidance showing suppressed daytime temperatures amid widespread cloud cover, intermittent showers, and northerly winds of 25–35 km/h that advect cooler maritime air. Midday readings hover near 18–19°C under overcast skies, with official Turkish Meteorological Service forecasts and international guidance (GFS/ECMWF) indicating a maximum around 19–21°C before precipitation and reduced insolation cap further warming. Seasonal norms for late September are higher (~23°C), but an incoming frontal system has driven temperatures below average. A realistic challenge would require earlier clearing of clouds or lighter rainfall than modeled, potentially allowing brief solar heating to reach 20–21°C before resolution criteria finalize the daily maximum.