Official National Weather Service observations recorded a maximum temperature of 87°F at San Francisco International Airport on September 8, 2026, exceeding the seasonal normal of 75°F by 12 degrees under hazy conditions with light winds. This verified measurement directly supports the market's 100% implied probability on the 86-87°F bin, as prediction markets aggregate trader assessments of official resolution criteria such as NWS climatological reports. Historical September highs average near 71°F, making this outlier event consistent with recent warm anomalies but still within record bounds. Minor adjustments to station data or alternative downtown readings could theoretically shift the exact bin, though the consensus outcome aligns closely with primary agency reports and leaves little room for revision.