Marine layer stratus and persistent onshore flow from the Pacific are keeping San Francisco highs suppressed near or slightly below the mid-August climatological normal of 67–73°F at SFO. National Weather Service and AccuWeather guidance point to morning clouds and a moderate sea breeze limiting afternoon solar heating, favoring the market-leading 70–71°F bin at 39% implied probability over 72–73°F. Minor model spread hinges on inversion strength and exact clearance timing: a weaker marine layer could allow brief warming into the low 70s, while lingering fog or stronger westerlies would cap readings closer to 68–69°F. No anomalous heat signals or offshore flow have emerged to support higher bins.