The National Weather Service official climate summary recorded a maximum temperature of 73°F at San Francisco International Airport on September 15, 2026, aligning precisely with the market's dominant 72-73°F outcome. This result reflected typical September marine-layer conditions along the California coast, where cool Pacific waters and onshore flow suppressed warming below the 1991-2020 normal high of 75°F. Persistent fog, haze, and moderate westerly winds further limited daytime heating, consistent with historical patterns for the date. A stronger offshore flow or delayed marine intrusion could have pushed readings into the mid-70s or higher, but no such shift occurred in the final forecast models or observations.