**Trader consensus centers on a minimum temperature of 13–15 °C for Mexico City on August 21, 2026, reflecting typical late-summer nocturnal conditions at the city’s 2,240 m elevation.** August climatology shows average overnight lows near 13 °C (56 °F), driven by radiative cooling under partly cloudy skies once daytime heating and convective activity subside. Current forecast guidance from multiple models indicates a daytime peak near 25–26 °C with scattered afternoon showers, followed by clearing or broken cloud cover overnight that favors moderate cooling but limits extreme drops. Cloud cover and residual moisture from the rainy season act as a thermal blanket, while light winds reduce mixing that could otherwise produce lower readings. These factors position 15 °C as the modal outcome (60 % implied probability) with nearby bins at 13–14 °C also heavily favored, consistent with historical August variability and the absence of any anomalous high-pressure or clear-sky setup that would push minima below 12 °C or above 16 °C. No recent model shifts or observed anomalies have altered this range.