Forecast models from sources including the Met Office and timeanddate indicate a likely daily high near 39–41 °C in Jeddah on August 17, driven by persistent high pressure, light winds, and Red Sea moisture that limits cloud cover while sustaining heat. Coastal moderation keeps extremes below inland Saudi peaks, yet afternoon heating and low humidity push readings toward the upper end of recent climatological norms near 38 °C. Minor model spread around exact timing of peak warmth and any scattered afternoon clouds creates the tight distribution across 39–41 °C outcomes, with traders weighting the most probable measured value at the official King Abdulaziz International Airport station. Updated guidance issued in the past 48 hours has not shifted the central tendency, keeping the market closely balanced until final observations resolve the range.