Forecast models from sources including the National Weather Service equivalents and European ensembles indicate Mexico City's overnight minimum on September 9 will likely settle near 12–13 °C under persistent cloud cover, light northerly winds, and scattered rain from the ongoing wet-season pattern. These conditions suppress radiative cooling at the city's 2,240 m elevation, keeping temperatures close to seasonal norms rather than allowing the sharper drops that occur under clear, calm skies. Trader sentiment remains split between the 16 °C-or-higher bucket and the 6 °C-or-below bucket because ensemble spreads show modest sensitivity to exact cloud timing and boundary-layer moisture; small forecast shifts could push the realized low either above 15 °C or, less likely, toward single digits if drier air arrives. Updated model runs and official minimum observations expected overnight will clarify the outcome.