The market consensus on a 76-77°F high for Seattle on September 17 reflects official observations from Seattle-Tacoma International Airport, where the daily maximum reached that narrow band under clear skies and light northerly flow. This outcome aligns with late-summer climatology, as regional high-pressure ridging suppressed marine air intrusion and allowed daytime heating to peak near the upper end of seasonal norms. National Weather Service preliminary climatological data and nearby station reports confirmed the reading without revision. Only an unexpected station-specific anomaly, measurement error, or post hoc quality-control adjustment outside standard NOAA protocols could alter resolution.