Official observations and forecast models aligned on a minimum temperature of 14°C in Mexico City on September 10, 2026, producing the market's 99.5% implied probability for that outcome. Light winds, moderate humidity, and limited overnight radiational cooling under partly cloudy skies prevented deeper drops, consistent with typical early-September climatology where nocturnal lows average near 13–14°C. Trader consensus reflects verified station data and narrow uncertainty ranges in real-time guidance. A modest revision in official records, a localized cold pocket at the measurement site, or post-event data adjustments could still shift resolution, though such changes appear unlikely given the tight model agreement.