**The official National Weather Service observation at San Francisco International Airport (KSFO) recorded a maximum of 85°F on September 10, 2026, directly anchoring the market’s near-certain 84-85°F outcome.** This value fell well above the long-term normal of 75°F yet remained below the prior-day peak of 94°F during the same late-summer heat wave. A strong offshore flow and delayed sea breeze allowed inland warming to reach the coast midday before moderating afternoon winds brought slight relief. The 85°F reading sits comfortably inside the market’s dominant bin while exceeding the 89°F all-time September 10 record only in the sense that it matched a near-record warm day without surpassing it. Resolution hinges on the single authoritative KSFO maximum; alternative stations, preliminary spot readings, or post-hoc quality-control adjustments could theoretically shift the final figure, though such revisions are rare once the daily climate summary is issued. Traders priced in the observed data with essentially full certainty once the NWS preliminary report confirmed the exact threshold.