Persistent marine layer and moderate onshore flow from the Pacific are capping daytime heating in San Francisco on August 12, keeping official highs (typically measured at KSFO) centered in the 69–72°F range according to National Weather Service and private model guidance. This setup, reinforced by the cool California Current and coastal upwelling, produces frequent low stratus and fog that limit solar insolation even as interior valleys warm. Trader consensus reflected in the closely matched 70–71°F and 72–73°F contracts aligns with this typical late-summer pattern, while lower-probability outcomes hinge on unexpected layer erosion or stronger offshore flow. Updated NWS point forecasts and hourly observations will refine resolution as the day progresses.