Official observations from National Weather Service stations in the San Francisco Bay Area recorded a daily maximum of 70–71°F on September 17, 2026, aligning with the market’s near-certain consensus for that bin. Marine layer influence and persistent onshore flow kept temperatures below seasonal normals of 74–76°F, preventing the brief warming that sometimes occurs under clear skies or offshore winds. This outcome matches climatological patterns for mid-September, when coastal upwelling and stratus typically suppress highs. A shift to 72°F or higher would have required either a stronger thermal trough or delayed marine intrusion—conditions not supported by the day’s synoptic setup or real-time sensor data.