Official climate summaries from the National Weather Service confirm a minimum of 51°F downtown San Francisco and 52°F at the airport on October 11, 2026, falling 3–4°F below the 1991–2020 normal of 55°F. Overnight radiational cooling under mostly clear skies, combined with a moderate onshore flow and residual marine layer influence from the Pacific, produced these values without significant fog or cloud cover to retain heat. Hourly METAR observations at KSFO showed the lowest readings near dawn, consistent with typical autumn patterns where coastal upwelling keeps highs modest and allows the daily range to reach 10–15°F. The near-even market-implied odds between the 50–51°F and 52–53°F bins reflect uncertainty over which station or microclimate reading would define resolution, while lower-probability colder outcomes were limited by the absence of stronger northerly flow or clear-sky amplification that would push temperatures below the historical low of 49°F for the date.