Current forecast models indicate a daily minimum temperature in Buenos Aires on September 27 likely near 14–16°C, driven by easterly winds and increasing cloud cover that limit nocturnal radiative cooling. Multiple runs from ECMWF and similar systems show highs around 19–20°C with a 40–60% chance of showers or thunderstorms, which typically raise overnight lows by trapping heat compared to clear-sky conditions. This setup creates tight market-implied odds between sub-10°C and 20°C+ outcomes, as small shifts in cloud timing or wind strength could alter the exact minimum by several degrees. Historical September averages for the city hover near 12–15°C lows, providing context for the current range. Updated model guidance and observational data over the next 48 hours will likely narrow the uncertainty ahead of resolution.