**Recent forecasts and model runs for Mexico City on August 29 point to overnight lows in the 10–13°C range, with some projections dipping to 9°C or below in higher-elevation or suburban zones, driving the 40.5% market-implied probability for that outcome.** Mexico City’s 2,240 m elevation amplifies nocturnal cooling under the influence of a lingering cooler air mass, as evidenced by the August 24 cold alert that brought minima as low as 8°C in western boroughs. Persistent cloud cover and scattered showers associated with the rainy season limit radiative cooling but also keep daytime highs modest (around 19–23°C), allowing temperatures to fall steadily after sunset. Official and private forecasts (including hourly data showing early-morning readings near 10°C) create genuine uncertainty around the exact minimum at the resolution station, which explains why multiple mid-teens outcomes cluster near 26% while the tail risk of 9°C or below commands the highest single probability. Historical August climatology (typical lows 10–12°C) provides context, but the current synoptic pattern has shifted trader consensus toward the cooler side of the distribution ahead of final observations.