**Official observations from Toronto-area stations, including Pearson International Airport, recorded a minimum temperature of 16°C overnight into September 17, 2026, driving the near-certain market consensus at that level.** Mild conditions prevailed under mostly cloudy skies and light northerly winds, which limited radiative cooling and kept the overnight low above the seasonal average of roughly 13.5°C. Hourly data showed temperatures bottoming out near 16°C before rising through the morning, consistent with regional model guidance and real-time reports. This outcome aligns with broader September warmth across southern Ontario, where departures of +3°C or more from normal have been common. While measurement revisions or differences across micro-sites remain theoretically possible, the agreement across multiple authoritative sources makes a shift below 16°C highly improbable.