Persistent marine-layer stratus and a steady onshore sea breeze from the Pacific suppressed daytime heating in San Francisco on August 7, producing an official high of 66–67 °F at the KSFO station. This outcome aligns with climatological norms for early August, when coastal upwelling and the typical afternoon sea breeze cap maxima in the upper 60s to low 70s even as interior valleys warm. Model guidance and National Weather Service observations confirmed limited ridging and no offshore flow that could have allowed stronger solar heating. While instrument calibration differences or micro-climate variations at unofficial sites could theoretically alter readings, the market’s 100 % consensus on 66–67 °F reflects the standardized resolution criteria and the absence of any credible conflicting data.