National Weather Service and private model guidance for San Francisco on August 12 project a high near 69–72 °F, driven by a persistent marine layer and moderate onshore flow from the cool Pacific that caps daytime warming. This coastal regime, typical of August climatology averaging 69 °F, produces the market’s concentration on the 68–73 °F bins. Small differences among those outcomes hinge on forecast details such as the exact timing of any afternoon clearing, subtle shifts in wind speed, and minor model spread in boundary-layer mixing; stronger or more persistent stratus would favor the lower side, while brief thinning could push readings toward 72–73 °F. No significant offshore flow or heat advection is expected to elevate temperatures beyond the current 70–71 °F favorite.