**Trader sentiment for the lowest temperature in Mexico City on August 30 reflects tight clustering around 11–14°C, driven by forecast uncertainty in overnight radiative cooling amid the rainy season.** Multiple models show minimums near 11–13°C, consistent with recent late-August observations (typically 12–14°C) at the city’s high elevation of roughly 2,240 meters, where thinner atmosphere allows faster heat loss after sunset. Persistent cloud cover and scattered showers—forecast at 40–60% probability—limit clear-sky cooling by trapping longwave radiation and adding latent heat from precipitation, while light winds (2–6 mph) reduce mixing that could otherwise moderate the drop. Humidity near 70–90% and dew points around 12°C further influence the rate of temperature decline, with model spreads arising from differences in predicted cloud thickness and timing of any rain. The elevated probability on 6°C or below (27%) likely captures tail risk from stronger-than-expected clearing, though current guidance and historical analogs make such extremes unlikely. Upcoming model runs and evening observations will refine these variables before resolution.