Official National Weather Service observations from Seattle-Tacoma International Airport recorded a daily maximum of 78°F on September 9, 2026, under partly cloudy skies with light winds and no significant precipitation, placing the outcome firmly in the 76-77°F range according to trader consensus. This aligns with near-normal late-summer conditions, where the airport's climatological average high is 74°F and recent model guidance showed minimal deviation from seasonal baselines. The overwhelming market-implied probability reflects verified post-event data from authoritative monitoring sources, with traders incorporating real-time station reports and historical analogs for similar September setups. Only substantial revisions to official records or a shift to an alternate measurement site could alter resolution, though such changes remain unlikely given the consistency of preliminary climatological summaries.