Official temperature records from Environment and Climate Change Canada and station observations confirm a daily maximum of 25°C in Toronto on September 4, 2026, aligning with the market's near-certain outcome. This value sits slightly above the 1991–2020 climatological average high of 24.1°C for the date, driven by clear to partly cloudy conditions, light northwesterly winds, and minimal cloud cover that allowed efficient daytime heating without significant precipitation or cooling. Traders incorporated real-time forecasts from Environment Canada and model consensus projecting a peak near 25–26°C, with post-event verification locking in the result. While station discrepancies or data revisions remain theoretically possible, such adjustments are rare for established urban sites and would require substantial new evidence to shift the outcome.