Recent forecast consensus from GFS and ECMWF runs positions a 20°C daily maximum as the most probable outcome for Istanbul on October 5, driven by a stable high-pressure ridge and persistent northeasterly flow that limits daytime heating and moisture influx. Model guidance shows partly cloudy skies with light winds shifting southeast by afternoon, yielding afternoon peaks near 20–21°C and aligning closely with early-October climatological normals of 19–20°C. Minor ensemble spread around 19–22°C reflects typical boundary-layer variability rather than major synoptic shifts, supporting the market’s concentration on those three bins. Updated model runs and surface observations through October 4 will refine the precise peak before resolution.