Recent forecasts from models including ECMWF and GFS indicate afternoon highs in Jeddah likely reaching 36–38 °C on September 17, with 37 °C and 38 °C outcomes nearly tied as traders weigh subtle differences in peak solar heating and sea-breeze timing. Clear skies and light southwesterly winds promote strong insolation over the coastal plain, while Red Sea moisture keeps relative humidity moderate and limits extreme spikes above historical September baselines near 36 °C. Minor model spread in the exact timing of onshore flow and boundary-layer mixing creates the narrow gap between the leading probabilities, with new observational data from local stations expected to resolve the outcome by evening.