Traders favor 29–31°C as the lowest temperature in Jeddah on August 22 because official forecasts and model guidance show overnight minima clustered in this narrow band amid typical late-summer conditions. The Red Sea’s high humidity and moderate sea-surface temperatures limit radiative cooling after sunset, while light westerly winds and generally clear skies promote steady nocturnal temperature drops without strong advection of cooler air. Recent observations confirm daytime highs near 37–40°C and prior-night lows of 28–31°C, consistent with climatological August averages. Minor forecast spreads arise from small differences in predicted cloud cover and boundary-layer mixing, which can shift the minimum by 1–2°C. No significant synoptic changes or data revisions have altered this consensus in the past 48 hours.