**National Weather Service and model guidance for August 25, 2026, center on a high near 72°F under mostly sunny conditions with moderate onshore flow.** This places the strongest market-implied probability (30.5%) on the 72–73°F bin, followed closely by 70–71°F (26.0%) and 74–75°F (22.5%), reflecting tight clustering around climatological norms for late August in San Francisco. The marine layer—persistent stratus and fog driven by the eastern Pacific trough and high pressure over the interior West—remains the dominant control. Its depth, timing of any afternoon clearing, and interaction with west-to-northwest winds determine how much solar heating reaches the surface at the official observation site. A slightly stronger or more persistent cloud deck favors the lower 70s or upper 60s, while modest thinning or delayed marine intrusion supports the mid-70s. Historical analogs show San Francisco highs vary sharply day-to-day within a 64–79°F envelope precisely because of these coastal dynamics, with no major synoptic shift indicated through the period.