National Weather Service and private forecast models show strong consensus for an overnight low in the upper 50s°F on August 22, driven by a persistent marine layer and typical onshore flow from the Pacific that moderates San Francisco temperatures. This aligns closely with the market's leading outcomes clustered around 56–59°F, which match recent observations of 56–58°F lows and the long-term August average near 56°F. No major synoptic changes, such as ridge strengthening or anomalous clearing, appear in current ensemble runs, limiting upside or downside tail risks. Traders are weighting official guidance heavily, with smaller probabilities assigned to deviations that would require atypical wind shifts or marine layer compression.