San Francisco's marine-influenced climate creates tight uncertainty for the August 25 low temperature, with forecast models showing a narrow range centered on 52–63°F due to variable overnight cooling from the Pacific. Onshore flow and the marine layer—enhanced by coastal upwelling—typically suppress minima near the seasonal average of 54–58°F, but subtle shifts in wind direction or fog timing can add or subtract several degrees. Current National Weather Service guidance and ensemble runs indicate modest disagreement on the strength of the inversion layer overnight, keeping probabilities clustered around the 52–59°F bins while lower odds on extremes reflect historical rarity of sub-50°F or above-65°F readings in late summer. Updated model cycles through the next 24 hours will likely refine the precise minimum.