Official measurements from Environment Canada at Toronto Pearson International Airport, the designated resolution station, recorded a daily maximum of 20°C on May 15 under mainly sunny skies and light southerly flow. This outcome aligned closely with seasonal climatological norms near 19–20°C and consensus guidance from the GEM, GFS, and ECMWF models, which projected modest boundary-layer warming without significant advection or cloud cover to suppress peaks. The market’s near-certain pricing at 20°C reflects trader recognition that station-specific data, rather than downtown urban heat-island effects, governs resolution. Only an unreported sensor anomaly or post-analysis revision could alter the result, scenarios with negligible probability given standard verification protocols.