The market's overwhelming consensus on a 64–65°F high for San Francisco on May 15 reflects National Weather Service observations at key stations, including San Francisco International Airport, confirming a peak temperature locked in that narrow band. Persistent marine-layer stratus and moderate onshore flow from the Pacific kept daytime warming suppressed, consistent with the city’s spring climatology where highs average near 64°F under typical coastal conditions. Global Forecast System and European Centre for Medium-Range Weather Forecasts runs showed strong agreement on this outcome through the preceding 48 hours, with no sign of the clear skies or offshore winds needed to push readings to 66°F or higher. A realistic challenge would require an abrupt shift in the sea-breeze regime or a rare warm-air advection event, neither of which appeared in final verified data.