**Persistent marine layer cooling from the cold Pacific Ocean and California Current continues to dominate San Francisco conditions on August 28, 2026, keeping the daily maximum at SFO tightly clustered in the mid-to-upper 60s.** Official National Weather Service guidance calls for a high near 69°F under mostly cloudy to partly sunny skies after morning low clouds or a slight shower chance, with moderate west-to-northwest winds of 7–15 mph (gusts to 23 mph) maintaining onshore flow. This setup reflects the typical summer pattern in which coastal upwelling sustains ocean surface temperatures around 55–58°F, while the shallow marine layer caps solar heating and prevents significant warming despite seasonal norms. Recent model consensus and observations show the layer remaining stable rather than eroding quickly, limiting upside potential above 71°F while also capping downside risk below 66°F absent unusually strong fog or wind. The closely bunched market probabilities around 66–71°F (nearly 80% combined) reflect this narrow forecast envelope and the inherent uncertainty in exact afternoon clearing timing and inversion strength, with traders weighting the NWS point forecast and historical analogs for late-August coastal maxima.