**Trader sentiment for San Francisco’s August 10 high temperature centers on the 70–73°F range (combined ~64.5% implied probability), reflecting typical late-summer coastal moderation amid variable marine-layer influence.** The city’s temperatures are shaped primarily by the strength and depth of the marine layer—a cool, moist air mass from the Pacific that often produces low stratus, fog, and onshore flow. This keeps highs well below inland values, with sea breezes and upwelling of cooler ocean water further limiting warming. Recent National Weather Service discussions note a returning or compressed marine layer after periods of stronger onshore push, which has held coastal readings in the mid-to-upper 60s while interior valleys reached the 90s–100s. Long-term August climatology shows average highs near 69–70°F, with rare excursions above 75°F. Forecast models for the 10th currently cluster in the upper 60s to low 70s, producing the tight split between the 70–71°F and 72–73°F bins. Subtle differences in predicted wind direction, marine-layer depth, or any late-day clearing could shift the outcome by a degree or two. With no strong offshore flow or heat surge expected to reach the immediate coast, traders see little support for outcomes above 75°F or below 68°F.