Trader consensus on Polymarket assigns a near-certain 100% implied probability to a highest temperature of 62-63°F in San Francisco on April 15, 2026, driven by verified observational data from the National Weather Service Automated Surface Observing System (ASOS) at San Francisco International Airport (KSFO), the market's official resolution source. Hourly records confirm a peak of 62°F amid persistent low marine layer, westerly winds of 15-25 mph, and partial cloud cover, keeping readings below the climatological April average of 65°F. Pre-event NOAA forecast models like GFS and ECMWF accurately predicted this cool regime due to strong onshore flow and cool Pacific sea-surface temperatures around 57°F. Resolution is straightforward absent rare post hoc data revisions from quality control, such as recalibrated sensor readings elevating the peak to 64°F—highly improbable given consistent mid-afternoon maxima around 60-62°F.