Mexico City's high elevation of roughly 2,240 meters drives consistently mild summer minimum temperatures, with August climatology showing typical overnight lows of 12–15 °C under the influence of the rainy season. On August 21, 2026, current forecasts from models and agencies point to partly cloudy to overcast skies with scattered showers, which limit nocturnal radiative cooling and keep the daily minimum near the upper end of the historical range. Key differentiating factors among the closely matched 13–15 °C outcomes include exact timing and intensity of cloud cover or rainfall—thicker clouds or earlier precipitation trap heat and raise the low by 1–2 °C—along with minor variations in wind speed, humidity, and urban heat-island effects across measurement stations. These elements create the narrow probability spread traders currently reflect.