Recent official forecasts from agencies including the Met Office and multiple numerical models consistently project a maximum temperature of 19–20 °C for Istanbul on October 4, 2026, under mostly sunny skies and moderate northeast winds. This aligns closely with the city’s long-term early-October climatology, where average daily highs reach about 20 °C. The strong market weighting on 19 °C (57 %) and 20 °C (37.5 %) reflects this model consensus and the absence of significant synoptic shifts, such as warm advection or cold fronts, that could push readings outside this narrow range. With resolution imminent, traders appear to view deviations to 21 °C or below 18 °C as low-probability outliers given current observational trends and ensemble guidance.