Official National Weather Service observations at San Francisco International Airport recorded a minimum temperature of 59°F on August 25, 2026, aligning precisely with the dominant 58-59°F market bin. Persistent marine-layer stratus and onshore flow maintained typical late-summer nocturnal cooling without the stronger radiational or offshore-wind conditions that historically produce sub-55°F readings. Model guidance and local climatology had already converged on lows in the upper 50s, and post-event verification eliminated remaining uncertainty, driving near-certain trader consensus. Only minor station-to-station variance or measurement timing differences could theoretically shift resolution, but authoritative data sources render such scenarios improbable.