**Forecast consensus points to an overnight low near 20–22°C in Istanbul on September 4, 2026, under mostly clear to partly cloudy skies with light northeasterly winds.** Multiple models (including ECMWF, GFS, and local Turkish sources) show daytime highs of 27–29°C transitioning to nighttime minima of 19–22°C, consistent with late-summer conditions moderated by the Bosphorus and Sea of Marmara. The tight clustering of market-implied probabilities around 17–23°C (all near 49–50.5%) reflects genuine forecast uncertainty rather than divergent outlooks. Key differentiating factors include the precise strength of nocturnal radiative cooling under variable cloud cover, boundary-layer mixing from sustained 5–10 m/s winds, and small differences in dew-point depressions that affect how low surface temperatures can drop before sunrise. Coastal stations may record 1–2°C warmer minima than inland areas due to maritime influence. No significant synoptic changes—such as frontal passages or increased cloudiness—are expected in the next 48 hours, keeping probabilities anchored near recent ensemble means while leaving room for 1–2°C model-to-model spread in the final observed minimum.