Recent National Weather Service guidance and model consensus point to a persistent deep marine layer and onshore westerly flow keeping San Francisco’s August 15 high in the upper 60s to low 70s, with specific point forecasts centering on 68–70 °F. This setup follows a multi-day cooling trend driven by upper-level troughing that has maintained below-normal temperatures and elevated the marine inversion, limiting afternoon warming despite subtle ridging expected to begin Saturday. Traders have priced the 68–69 °F bin highest because it matches the most frequent official runs and historical analogs for similar marine-dominated patterns, while the 70–71 °F tier captures the modest upside risk from any earlier clearing or lighter winds. The narrow distribution around these bins reflects low uncertainty in the short-term forecast window, with resolution hinging on the precise peak reading at official SF stations under continued onshore flow.