Recent National Weather Service and model guidance indicate a persistent marine layer and onshore flow keeping San Francisco highs near or slightly below the early-September climatological average of ~70°F, with most forecasts centering on 65–69°F for September 2. Trader emphasis on the 70–71°F and 72–73°F bins reflects uncertainty in the exact timing of any afternoon clearing or modest offshore warming, which could allow brief solar heating to push readings into the low 70s despite the broader trough favoring below-normal temperatures across northern California. Key differentiators include the strength of the inversion capping the marine layer, wind shifts that modulate cool-air advection, and precise cloud-cover evolution during peak heating hours, all of which remain sensitive to the next 48-hour model updates from the National Weather Service.