**Trader sentiment for San Francisco’s August 4 high temperature centers on the 72–73 °F bin (29.5 % implied probability) because official National Weather Service and model guidance currently favor a moderate onshore flow that limits warming.** Persistent marine-layer stratus and a steady westerly sea breeze advect cool Pacific air across the coast, capping daytime maxima near the seasonal 70–73 °F normal despite a broad high-pressure ridge driving inland heat. Slight differences among the tightly clustered 72–77 °F outcomes hinge on the precise timing and depth of any afternoon clearing, the strength of the thermal gradient that sustains the sea breeze, and small variations in 850 hPa temperatures or boundary-layer mixing. Recent forecast discussions note minimal offshore flow or subsidence warming through early August, keeping higher bins (≥78 °F) at low single-digit probabilities while still leaving room for modest day-to-day shifts as new model runs arrive.