**Recent forecasts indicate minimum temperatures in Jeddah on September 10 are most likely to fall in the upper 20s °C, driven by persistent Red Sea marine influence that limits nocturnal cooling under typical September conditions of high humidity and light winds.** Official and ensemble model guidance (including ECMWF and GFS runs referenced in public forecasts) consistently project overnight lows near 28–29°C, with daytime highs reaching 37–40°C amid mostly clear to partly cloudy skies and negligible precipitation risk. This aligns with the month’s climatological pattern, where average September minima hover around 26–28°C but have run 1–2°C above normal in early September 2026 observations from Jeddah stations. The closely matched market-implied odds between 24°C or below (49%) and 34°C or higher (47%) reflect trader focus on the tail risks of greater-than-expected radiative cooling versus suppressed cooling. Key differentiating factors include Red Sea sea-surface temperatures near 30–31°C sustaining dew points in the mid-20s °C and high relative humidity (often 60–80% overnight), which reduces net longwave heat loss; variable low-level wind speeds and directions that can either enhance mixing or allow localized pooling of cooler air; and any late shifts in cloud cover that alter the surface energy balance. With resolution hinging on the official daily minimum (typically the lowest hourly reading at the primary Jeddah station), traders are monitoring the next 24–48 hours of model updates for any adjustments to the nocturnal boundary layer forecast. Historical analogs show that deviations beyond ±2–3°C from guidance are uncommon this close to the date in the absence of unusual synoptic features.