Recent National Weather Service and ensemble model guidance points to a September 4 overnight low in the mid- to upper-50s°F for San Francisco, driven by a persistent marine layer and moderate onshore flow that limits radiative cooling despite clearing skies. Subtle differences among forecast runs—particularly the depth of the marine inversion, timing of any residual drizzle, and exact wind speeds near 10–15 mph from the west—create tight clustering around 54–57°F bins, while the elevated probability on 66°F+ reflects residual model spread and the possibility of stronger mixing if winds increase. Historical climatology shows an average low near 56°F, so current conditions align closely with norms but remain sensitive to small shifts in Pacific high pressure and coastal fog persistence ahead of the next model update.