Current ensemble forecasts from NOAA models point to a typical late-summer marine layer over San Francisco, supporting an overnight low in the mid-to-upper 50s°F on August 26 amid light onshore flow and possible patchy fog. This climatological baseline—average August lows near 57°F—explains the tight clustering of market-implied odds around the 52–59°F bins, as traders weigh minor differences in radiational cooling under variable cloud cover versus stronger sea breezes that could limit the drop. Key uncertainties include the precise timing of fog intrusion and wind speeds at official stations like KSFO, which can shift the minimum by 2–4°F; updated model runs and local observations over the next 24 hours will likely refine these probabilities further.