Forecast models and official Servicio Meteorológico Nacional guidance for Mexico City on August 28 indicate a minimum temperature of 13–15 °C, driven by the city’s 2,240 m elevation promoting strong nocturnal radiative cooling during the rainy season. Afternoon convective clouds and scattered showers, typical of the North American monsoon pattern, can trap longwave radiation and raise overnight lows, while clearer intervals allow faster heat loss. Recent model runs show modest spread in cloud timing and humidity, producing the tight clustering of market-implied odds around 13–15 °C; lighter winds reduce mixing and favor slightly lower readings in sheltered urban stations. Historical August minima average near 10–13 °C, providing context for why traders assign limited probability to extremes below 11 °C or above 17 °C absent major forecast shifts.