Recent National Weather Service and private model guidance for San Francisco points to a typical early-September marine layer regime, with onshore westerly flow and coastal stratus limiting overnight radiative cooling. Ensemble forecasts converge on a minimum temperature near 56°F, consistent with the 1991–2020 climatological average low of 56.1°F for the date and recent observed minima in the mid- to upper-50s. The market’s tight clustering between 54–57°F reflects this consensus, while the elevated share for 66°F or higher likely captures residual uncertainty in marine-intrusion timing or model spread on boundary-layer mixing. No significant synoptic shifts—such as offshore flow or stronger high pressure—are projected through the 48-hour window, keeping resolution thresholds tightly linked to the strength and persistence of the marine layer.