**Recent polar air advection has driven cooler-than-average overnight lows in Buenos Aires, with short-range forecasts from multiple models converging on a September 7 minimum near 5–7 °C.** A strong southwest flow and clear skies on September 5 produced lows around 3–4 °C, but northerly winds and gradual moderation are expected to lift the September 7 overnight low several degrees while still remaining below the long-term September climatological minimum of ~9 °C. Key differentiating factors among the closely matched market outcomes include the precise timing of the wind shift from southerly to northerly, the degree of nocturnal radiative cooling under partly cloudy skies, and any small discrepancies between ensemble members in boundary-layer moisture and 850 hPa temperatures. Official monitoring (e.g., Servicio Meteorológico Nacional) and global model consensus currently favor values in the mid-single digits, yet the 1–2 °C spread typical of 48-hour forecasts keeps several adjacent buckets competitive. Updated model runs and local observations over the next 24–48 hours will narrow the range and likely shift implied probabilities.