Forecast models for Jeddah on August 20 point to a daytime maximum near 37–39 °C, consistent with the closely bunched market probabilities centered on 38 °C. The Red Sea’s high humidity and sea-breeze circulation typically cap peak temperatures a few degrees below inland Saudi values, while the region’s broader warmer-than-normal pattern through October—driven by persistent high pressure and reduced cloud cover—adds upward pressure. Key differentiating variables include exact timing of the sea breeze, boundary-layer moisture, and any short-wave trough that could enhance mixing or suppress the afternoon peak; ensemble spreads in these factors explain why 40 °C+ still carries meaningful probability despite historical August averages near 38 °C. Updated National Center for Meteorology guidance and regional model runs over the next 48 hours will narrow the range.