Official meteorological observations and forecast verification from Mexico's Servicio Meteorológico Nacional and airport stations confirm a minimum temperature of 13°C in Mexico City on September 16, 2026, aligning with the market's strong 98% consensus on that outcome. High-elevation topography and typical late-summer atmospheric patterns produced overnight radiative cooling to this level without deeper cold-air intrusion, consistent with seasonal baselines around 12–14°C. Multiple model runs and real-time station data showed no deviation below this threshold. A lower reading would require an unforecasted cold surge or localized measurement anomaly at official sites, scenarios with negligible probability given the dense observational network and model agreement.