Recent forecasts from multiple models indicate Mexico City’s overnight low on September 23 will likely settle in the 13–15 °C range, shaped by the city’s 2,240 m elevation that promotes strong nocturnal radiative cooling under partly cloudy skies typical of the late rainy season. Persistent moisture and light winds limit extreme drops, while any clearer intervals could briefly push readings toward the lower end of that band without reaching single digits. Trader sentiment remains nearly even between the 6 °C-or-below and 16 °C-or-higher bins because resolution hinges on the precise minimum recorded at official stations, where small variations in cloud cover or timing of showers can shift the outcome by a degree or two. Updated model runs over the next 48 hours will clarify whether steering patterns favor drier air masses that enhance cooling or maintain the current mild equilibrium.