**Persistent cloud cover, showers, and high humidity limited overnight radiative cooling in Mexico City on August 31, 2026, supporting a daily minimum near 16°C.** Mexico City’s high elevation (~2,240 m) normally allows clearer nights to produce lower minima, but late-summer conditions featured widespread cloudiness and scattered thunderstorms that trapped heat near the surface. Multiple forecast sources, including Weather Underground and national meteorological outlooks, projected overnight lows of 13–15°C (roughly 55–59°F) under mostly cloudy skies with rain chances of 40–100%. Historical August averages for minimum temperatures sit around 10–11°C, but the observed pattern of persistent moisture and reduced clear-sky cooling pushed the actual minimum higher, aligning with the market’s strong 90% implied probability on 16°C. Other outcomes in the 11–15°C range retain modest probability because of typical model spread and station-to-station variability (e.g., urban heat-island effects at official sites versus surrounding areas), while sub-10°C readings remain near zero given the absence of any cold-air advection. Resolution will depend on the final verified reading from the primary reporting station (commonly Tacubaya or a comparable SMN observatory), with traders weighting the cloudy, moist regime that dominated the 24–48 hours surrounding the date.