Trader consensus on Polymarket prices a modest 26% implied probability for 66°F or higher as the leading outcome for San Francisco's May 3 high temperature, with tightly clustered odds around 60-66°F bins reflecting ensemble forecast uncertainty from National Weather Service guidance and models like GFS and ECMWF. This positioning stems from typical early May marine layer dynamics, where cool, moist Pacific air forms a low-level inversion trapping stratus clouds, often capping highs in the low 60s unless midday solar heating burns off the layer early amid weakening onshore flow. Historical climatology at official stations shows May 3 averages near 65°F with a 60-70°F range, but model spread of 4-6°F arises from variable inversion strength and high-pressure ridging offshore. New 00Z/12Z runs and NWS updates today could sharpen differentiation as resolution nears.