**Forecast model divergence on overnight cooling for September 16 creates the near-even split between sub-2°C and double-digit minimums in Buenos Aires.** Multiple numerical weather prediction runs show southeast winds strengthening overnight, advecting cooler maritime air and promoting radiational cooling under mostly clear skies, yet they differ sharply on the depth and timing of the coldest air mass. Some outputs indicate the low could reach 5–7°C or lower if winds remain light enough for strong surface decoupling; others keep readings near 10–11°C due to slightly stronger mixing or a modest warm-air advection component. This uncertainty aligns with typical early-spring variability in the Río de la Plata region, where polar air intrusions can produce rapid temperature drops but are modulated by local factors such as urban heat-island effects and exact wind speed. Traders appear to be weighting the most recent model consensus and any updated SMN guidance equally, resulting in the balanced market-implied probabilities between the coldest and mildest bins. New official forecasts or 00Z/12Z model runs expected overnight will likely resolve much of the spread before the minimum is recorded.