Recent National Weather Service and model guidance for San Francisco on September 15 points to a high near 70–72°F under partly cloudy skies, with marine layer and southwest breezes potentially limiting warming in the urban core. This follows a sharp cool-down from the September 9 peak of 94°F, the hottest reading so far this year, as onshore flow strengthens. Ensemble spreads and microclimate effects create genuine uncertainty across the 66–75°F range, where most market-implied probability sits, while the 23% odds on sub-64°F or 82°F+ outcomes reflect tail risks from stronger fog intrusion or clearer, warmer conditions. Official daily maximum from downtown observations will determine resolution.