Recent numerical weather prediction models from Argentina’s Servicio Meteorológico Nacional and international ensembles indicate a daytime maximum near 18°C for Buenos Aires on May 19, driven by moderate southerly flow, partly cloudy skies, and limited daytime heating typical of late autumn in the region. The tight clustering of market-implied odds around 17–19°C reflects genuine forecast uncertainty, with small differences in cloud cover, boundary-layer mixing, and weak frontal passages able to shift the peak by 1–2°C. Clearer conditions or brief northerly advection could support 19–20°C, while stronger onshore flow would favor the lower end near 17°C. These variables explain why traders assign comparable probabilities to the three leading outcomes while keeping higher or lower extremes at minimal implied odds.