**Current forecasts from multiple models show Mexico City overnight lows for September 30 clustering near 13–17°C under persistent overcast skies and rain, close to the September climatological average of around 13°C at the city's 2,240 m elevation.** Trader sentiment splits nearly evenly between an unusually cold outcome (≤8°C) and a mild one (≥18°C) because small differences in cloud cover, rainfall timing, and radiational cooling can shift the minimum several degrees in either direction. High humidity and frequent precipitation during the late rainy season typically limit nighttime temperature drops by trapping heat, while any clearing would enhance cooling at altitude. With resolution just 48 hours away, the next official model runs and observational updates from Mexican meteorological services will likely tighten the range and drive the final market adjustment.