Traders overwhelmingly favor 37°C as Jeddah’s highest temperature on September 13, reflecting consensus from regional forecast models that project this peak under stable Red Sea coastal conditions. September climatology in western Saudi Arabia typically features highs near 37°C, driven by high solar insolation, limited cloud cover, and warm sea-surface temperatures that moderate but sustain heat. Current observational trends and model agreement indicate little deviation from this baseline, with no major synoptic changes such as stronger onshore winds or increased humidity expected to suppress the maximum. Resolution hinges on official Saudi meteorological station readings for the calendar day; only an unforecasted surge in afternoon convection would realistically alter the outcome.