Recent forecasts and early observations for Mexico City on September 15 positioned a 13°C overnight minimum as the most likely outcome, aligning with the market's 87.5% implied probability for that threshold. September's rainy season typically brings afternoon convection and elevated humidity that limits daytime heating while allowing moderate radiative cooling at night under the city's 2,240-meter elevation. Model consensus from regional agencies showed lows stabilizing near 12–14°C amid light northerly winds and patchy cloud cover, consistent with climatological September averages around 10–12°C but tempered by the absence of stronger cold-air intrusions. Lower-probability outcomes below 10°C would require atypical clear-sky intensification or a frontal passage not supported by current data releases. Official station reports and any model revisions will determine final resolution as traders weigh these variables.