**Current forecasts from multiple meteorological sources point to an overnight low of 55–58°F for San Francisco on September 4, 2026, aligning closely with the market’s top-implied outcomes.** Persistent marine-layer influence and onshore westerly flow from the Pacific keep coastal temperatures moderated, limiting radiative cooling under mostly clear to partly cloudy skies. Model consensus shows highs near 67°F transitioning to overnight lows in the mid-to-upper 50s, consistent with the September climatological average low of 56.1°F and recent years’ observations (typically 55–57°F). No significant synoptic changes—such as a stronger offshore flow or anomalous warmth—are indicated in the latest runs, supporting the heavy weighting toward the 58–59°F bin (47%) and adjacent 54–55°F/56–57°F ranges. Traders appear to be pricing in the narrow uncertainty band typical of coastal microclimates, where small shifts in wind direction or fog timing can alter the minimum by a degree or two before official observations finalize the result.