A polar air mass advancing over central Argentina is driving the sharp temperature drop expected in Buenos Aires on September 6, with official Servicio Meteorológico Nacional guidance and multiple models indicating a minimum near 2°C under clear to partly cloudy skies and southerly winds. Radiative cooling overnight, combined with the cold advection and moderate wind speeds, supports surface readings potentially reaching or dipping just below 0°C in suburban areas, though urban heat island effects and exact timing of the coldest air may limit how low the official city minimum falls. Recent model runs show tight clustering around 1–3°C, creating the market’s heavy weighting toward sub-2°C outcomes while leaving room for slight revisions from the next forecast cycle.