The market-implied odds for San Francisco’s July 31 high temperature center on 72–73 °F at 32.5 percent, reflecting trader assessment of typical late-July conditions dominated by a persistent marine layer and strong onshore flow from the Pacific. These factors, reinforced by the coastal upwelling that maintains cool sea-surface temperatures, normally cap daytime maxima near the 70 °F seasonal average recorded at KSFO. Recent model guidance and monthly outlooks show daily highs clustered between 68–73 °F, with fog and low stratus limiting solar heating and keeping the distribution broad. Lower-probability warmer bins (74 °F+) would require reduced marine influence or brief offshore flow, while cooler outcomes hinge on deeper fog or stronger winds. The wide spread underscores forecast uncertainty in the final 24–48 hours before resolution, when updated NWS guidance and high-resolution model runs will clarify any shifts in the marine layer depth or wind regime.