Traders have converged on 39°C as the implied outcome for Jeddah’s highest temperature on August 12 due to consistent forecast guidance from regional models and observational data showing a typical mid-August peak under clear to scattered cloud conditions. Jeddah’s coastal location on the Red Sea sustains high humidity and sea-surface temperatures near 31°C, which limit nighttime cooling and support daytime maxima around the long-term August average of 38–39°C. Official guidance projects light northwesterly winds and minimal precipitation, aligning with historical patterns where extremes rarely deviate sharply without major synoptic shifts. A stronger-than-expected heat advection or suppressed marine layer could push readings to 40°C or above, while increased cloud cover or a temporary wind shift might cap the high closer to 37–38°C, though current model consensus leaves little room for such revisions before the daily maximum is recorded.