**Current forecasts for Istanbul point to a minimum temperature near 19–21°C on September 1, 2026, under stable high-pressure conditions with clear skies and light northeasterly winds.** Multiple models and meteorological sources (including 30-day outlooks updated August 30) show daytime highs of 28–30°C transitioning to overnight lows of 19–21°C, consistent with typical early-September climatology for the region but slightly above long-term averages due to persistent warm advection. Key scientific drivers include radiative cooling overnight, modulated by low cloud cover (forecast near zero), moderate humidity, and weak winds that limit mixing. These factors favor minimums in the upper teens to low 20s Celsius rather than extremes. Recent late-August observations of similar patterns—with minimal frontal activity or moisture intrusion—support continuity into early September, keeping probabilities concentrated around 19–22°C outcomes. The near-even market weighting across 26°C+ (30.0%), 16°C or below (29.5%), and mid-20s values reflects residual forecast uncertainty two days out, including potential model spread in boundary-layer cooling or minor synoptic shifts. Historical analogs show September minima rarely deviate sharply without strong cold-air outbreaks, which are not indicated in current guidance. Traders appear to balance the baseline forecast with tail risks from measurement variability or unmodeled local effects.