Recent National Weather Service and model consensus points to a minimum near 55–56°F for San Francisco on September 26, driven by persistent onshore southwest flow and a stable marine layer that limits overnight radiative cooling under partly to mostly cloudy skies. Typical late-September conditions feature average lows of 55.6°F, with light to moderate west winds suppressing both extreme cooling and any inland warming. Trader sentiment clusters tightly around 54–57°F outcomes because current guidance shows little spread in forecast lows, while lower-probability bins for 64°F+ or sub-52°F reflect the low likelihood of rapid pattern shifts before resolution. Updated model runs and official briefings tonight will provide the final data ahead of the overnight minimum.