**Trader sentiment for San Francisco’s September 12 highest temperature reflects a near-even split between the 68–69°F and 70–71°F bins, driven by official forecast guidance showing a mild day shaped by persistent marine influence.** Morning observations from multiple stations placed temperatures in the upper 50s, with forecasts from the National Weather Service, Weather Underground, and private models converging on a daytime peak near 66–68°F under partly cloudy to sunny skies, west winds of 15–30 mph, and no significant warming aloft. This aligns with climatological norms for early-to-mid September, when the Pacific high and onshore flow typically cap highs in the upper 60s to low 70s, well below the ~71°F seasonal average. The tight market spread captures uncertainty in the precise peak: stronger afternoon clearing or slight offshore flow could push readings into the low 70s, while continued stratus or stronger winds would keep them in the upper 60s. No major synoptic shifts or heat anomalies have emerged in recent days to alter the baseline outlook.