Official observations from Environment and Climate Change Canada stations in Toronto recorded a daily maximum of 16°C on October 3 under clear to mainly sunny conditions, light easterly winds, and minimal cloud cover that limited daytime heating. This aligned closely with ensemble model guidance and the seasonal baseline high near 18°C, producing a tight temperature range with no significant warm advection or downslope effects to push readings higher. Traders converged on the 16°C outcome as the market-implied probability reached 100 percent once preliminary data confirmed no exceedance. Revisions in final quality-controlled records, use of an alternate station for resolution, or post-event adjustments to the maximum could theoretically alter the outcome, though such changes remain rare for well-monitored urban sites.