Official meteorological observations from Environment Canada recorded a daily maximum of exactly 21°C in Toronto on May 16, aligning with the market-implied odds of near-certainty for that outcome. This result stems from a stable high-pressure system that suppressed daytime warming across southern Ontario, keeping afternoon temperatures from climbing further amid moderate humidity and light winds. Historical climatology for mid-May shows Toronto averages around 18–20°C, so the observed reading sits slightly above normal but well short of the thresholds needed for 22°C or higher. Traders appear confident because surface station data and reanalysis products leave little room for revision once final quality-controlled figures are posted. Only an improbable late correction to the official record or use of an alternate measurement site could shift the outcome.