**Forecast models from sources including the Servicio Meteorológico Nacional and international ensembles indicate a likely daily maximum of 24–26°C in Mexico City on September 25, driven by variable cloud cover, light easterly to northeasterly winds, and residual moisture from the monsoon trough that could limit daytime heating or allow brief clearing.** Recent observations show afternoon highs near 24–25°C under partly cloudy skies, with dew points in the low teens supporting modest instability but low precipitation chances in the core urban area. Historical September averages for the high-elevation basin hover around 23–25°C, so current guidance aligns closely with seasonal norms while model spread—particularly in boundary-layer mixing and insolation—explains the market’s emphasis on 26°C or above as the leading outcome. Updated National Meteorological Service briefings and morning soundings tomorrow will refine the exact peak before resolution.