Strong southwest winds and clearing skies behind a frontal passage on September 20 are the main drivers pushing trader focus toward a low near or below 7°C for Buenos Aires on the 21st. Multiple models indicate the minimum will occur in the pre-dawn hours under partly cloudy to clear conditions, with dew points falling into the low single digits Celsius and radiative cooling enhanced by 20–30 mph gusts. Official guidance from sources such as the Met Office and local forecasts centers on 5–10°C, creating the near-even split between the sub-7°C bucket (46.5% implied) and warmer outcomes. Model spread in overnight cloud cover and wind timing introduces the primary uncertainty, while historical September minima in the city rarely exceed 10°C under similar post-frontal setups. Updated model runs and official minimum readings expected by early morning will likely resolve the tight market.