Persistent marine layer and onshore westerly flow from the Pacific are anchoring trader expectations for San Francisco’s August 27 low near the upper 50s, consistent with NWS guidance of temperatures near or slightly below seasonal norms through Thursday. A shallow inversion (roughly 1,000–1,500 ft) and moderate northwest winds of 10–20 mph limit daytime heating and promote overnight radiative cooling under mostly cloudy skies, producing forecast minima of 58–60 °F. Historical climatology places the late-August average low near 56 °F, so current model consensus supports bins clustered around 58–61 °F while leaving modest probability on cooler outcomes if the marine layer deepens or winds slacken. No major pattern shift is expected before resolution.