**Trader sentiment for Mexico City's minimum temperature on August 21, 2026, centers on the 12–16°C range, with closely matched probabilities reflecting genuine forecast uncertainty at the city's high elevation of roughly 2,240 meters.** August's rainy-season conditions—frequent afternoon convection, variable cloud cover, and moderate humidity—modulate nighttime radiative cooling and produce typical overnight lows of 12–14°C (54–57°F) per climatological baselines from sources like Weatherspark and AccuWeather. Current model guidance shows minor spreads: BBC and several ensembles point to a 12°C low under partly cloudy skies with light northeasterly winds, while others allow 13–15°C depending on the exact timing of any showers or clearer intervals that enhance or suppress heat loss. These small differences in boundary-layer moisture, wind speed, and cloud persistence explain why no single outcome dominates. Official resolution will rely on verified station data (likely from the Mexico City/Licenciado Benito Juárez International Airport or central observatory), where even a 1°C shift from precipitation timing or urban heat-island effects can decide the exact minimum. The tight clustering of probabilities around the historical and forecast median underscores traders' assessment of model divergence and the narrow resolution window remaining in the overnight hours.