**Trader sentiment for Mexico City’s August 30 lowest temperature reflects genuine forecast uncertainty around the 12–14 °C range, with closely matched market-implied probabilities (roughly 26–27 % each for 10–14 °C) driven by typical late-summer variability in the high-altitude Valley of Mexico.** Official Servicio Meteorológico Nacional guidance and multiple numerical models project a minimum of 12–14 °C under partly to mostly cloudy skies, with light northeast winds and possible residual moisture from overnight showers. At Mexico City’s elevation of roughly 2,240–2,260 m, radiative cooling overnight is moderated by high humidity (often 70–90 %) and cloud cover that reduces outgoing longwave radiation. Afternoon convection and thunderstorm activity, common in the rainy season, can either clear skies for greater nighttime cooling or maintain a warmer boundary layer. Recent hourly data and model runs show the overnight low most likely occurring between 4–7 a.m. local time, with temperatures hovering near 12–13 °C at central stations; slight differences in exact clearing timing or urban heat-island effects can shift the recorded minimum by 1–2 °C. Earlier August cold outbreaks reached single digits in peripheral alcaldías, but current synoptic conditions lack the strong high-pressure subsidence needed for those extremes. With resolution dependent on the precise official minimum (typically from the Mexico City observatory or airport station), traders are pricing the narrow spread of plausible outcomes rather than a single dominant value.