Short-term forecast uncertainty around the marine layer and onshore flow is the main driver behind the closely matched market odds favoring a San Francisco high of 68–71°F on July 23. National Weather Service guidance and ensemble models show modest afternoon warming as stratus clears, with sea-surface temperatures near seasonal norms and light winds limiting further rise above the upper 60s. Historical July maxima average near 69°F, but day-to-day variability from coastal eddy timing and inversion strength creates genuine spread across the 66–73°F bins. Updated model runs and afternoon observations tomorrow will refine the exact peak before resolution.