**Forecast models from the National Weather Service and private providers consistently project an overnight low in the upper 50s for San Francisco on August 22, 2026, aligning with the market’s top three outcomes (58–59 °F at 43 %, 56–57 °F at 30 %, and 60–61 °F at 27 %).** Persistent marine-layer influence and moderate onshore westerly flow (10–20 mph) are expected to keep radiational cooling limited, while the absence of strong offshore winds or clear-sky extremes prevents deeper drops. Recent observations show downtown and airport lows of 56–58 °F, matching long-term August climatology (average low ~55.9 °F). No significant synoptic shifts—such as a stronger thermal trough or anomalous ridging—are indicated in the latest model runs, supporting the tight clustering around 56–59 °F. Traders appear to be weighting the official NWS guidance and ensemble consensus most heavily, with smaller probabilities assigned to tails that would require atypical clearing or wind shifts not currently forecast.