National Weather Service forecasts and real-time observations at San Francisco International Airport place the May 17 daytime maximum near the 68°F climatological normal, driving the market-implied odds of 100% for 68°F or higher. Persistent high-pressure ridging and light onshore flow have limited marine-layer intrusion, allowing afternoon temperatures to climb into the upper 60s or low 70s at KSFO, consistent with historical May patterns where similar synoptic setups produce highs at or above this threshold roughly 60% of the time. A late-day surge in stratus or an unexpected wind shift could cap readings in the mid-60s, but current model consensus shows low probability of such cooling before peak heating.