**Trader sentiment for Mexico City's lowest temperature on August 21, 2026, centers on the 12–15°C range, with 15°C leading at 60% implied probability.** This reflects consensus from official forecasts and numerical weather models showing overnight lows in that band under typical August conditions. Mexico City sits at roughly 2,240 meters elevation, so nocturnal radiative cooling routinely drops temperatures well below daytime highs even in the rainy season. Current model runs and station guidance (including from Mexican meteorological sources) point to a daytime peak near 24°C followed by evening thunderstorms and persistent cloud cover, which limit clear-sky cooling and keep the minimum around 13–16°C. Historical August averages place the typical low near 12–13°C, but increased humidity, precipitation, and reduced net longwave radiation tonight support a slightly milder floor. Recent data reinforce this positioning: multiple 10-day outlooks issued on August 21 forecast lows of 13–16°C (55–61°F), with cloud cover and scattered rain expected through the night. These conditions reduce the chance of sharper drops below 12°C while making extremes above 16°C or below 11°C unlikely. Traders are pricing the market-implied odds around the forecast consensus, with the tight clustering at 12–15°C capturing the narrow uncertainty band typical for a single-day minimum under active monsoon-like moisture.