Marine layer depth and onshore flow from the Pacific dominate trader positioning for San Francisco’s August 7 high temperature, with NWS guidance highlighting persistent stratus and moderate coastal cooling amid a broader upper-level ridge. This setup typically caps daily maxima near the long-term August average of 69–70°F, supporting the near-even 31.5% and 30.5% market-implied odds on the 70–71°F and 72–73°F bins. Minor differences in model consensus around marine layer erosion timing or afternoon wind shifts can easily tip the outcome between these adjacent ranges, while stronger onshore flow or delayed clearing would favor the lower cluster. Inland heat and fire-weather signals have little direct effect on the immediate coast, underscoring the localized influence of the marine layer on resolution.