Recent National Weather Service forecasts for San Francisco on September 29 project a minimum temperature near 55°F under mostly clear skies and light westerly winds, consistent with typical late-September marine layer moderation from Pacific onshore flow. This places the outcome in the 54-55°F or adjacent buckets, though model spreads and microclimate variations around the official station introduce uncertainty in the precise overnight low. Stronger marine influence or increased cloud cover could elevate minima, while clearer, calmer conditions might allow slight radiative cooling toward lower values. Historical September averages near 56°F provide baseline context, with traders weighting the latest model runs and any shifts in steering patterns ahead of final resolution.