Trader consensus on a 12°C low for Buenos Aires on October 13 reflects observed station data and model outputs showing overnight minima near that threshold amid a lingering cool air mass. Easterly to southeasterly winds advected moisture from the Río de la Plata, sustaining cloud cover and light drizzle that limited daytime heating while allowing radiative cooling under partly clear intervals at night. National Meteorological Service guidance and Open-Meteo analyses placed the daily range at roughly 13–19°C, with the lowest readings clustering around 12–13°C consistent with spring transitional patterns in the region. The near-certain market-implied probability for 12°C stems from this convergence of real-time measurements and historical analogs for similar synoptic setups. A modest revision could occur if the official Servicio Meteorológico Nacional station reports a slightly different minimum due to exact siting or hourly sampling differences.