**Trader consensus centers on a daily maximum of 25–26 °C, reflecting typical late-summer conditions in Mexico City’s subtropical highland climate.** September falls in the rainy season, when afternoon cloud cover, thunderstorms, and evaporative cooling from precipitation routinely cap daytime highs near the long-term average of 23–24 °C. Current forecasts for September 3, 2026, show partly cloudy skies with a 40–70 % chance of storms and highs of roughly 23–26 °C (78–79 °F), consistent with model runs emphasizing modest warming under variable insolation but limited by moisture and convection. The strong weighting toward 25 °C (51 %) and 26 °C (31.5 %) indicates traders view these as the most probable outcomes given the balance of seasonal norms and near-term model guidance. Lower probabilities for 24 °C or below align with the limited scope for significant cooling without atypical widespread rain or stronger cold-air advection, while odds for 27 °C or higher remain low because persistent cloudiness and storm activity suppress extreme warming. No major deviations from climatology or unexpected synoptic shifts appear in recent observations, keeping the market tightly clustered around the forecast range.