Recent National Weather Service guidance and ensemble model runs point to a modest warming trend for San Francisco on August 5 amid a broader California heat event, with the marine layer expected to limit coastal penetration. Onshore westerly flow and a shallow marine inversion typically cap daytime maxima near 70–75 °F at official stations, while reduced fog depth or a slight offshore component could allow readings into the mid-70s. The tight clustering of market-implied odds around the 70–75 °F bins reflects this narrow uncertainty range, with traders weighing the latest GFS and ECMWF solutions against climatological August averages near 70 °F. Stronger sea breezes or earlier clearing would favor the lower bins, whereas any ridge strengthening could push toward 76–77 °F.