Recent forecasts from Argentina’s Servicio Meteorológico Nacional and global models indicate a daytime high near 17–19 °C in Buenos Aires on May 18, driven by a post-frontal southerly flow that advects cooler maritime air and suppresses diurnal heating under partly cloudy skies. Seasonal transition into late autumn further lowers baseline temperatures below the May climatological average of 18–19 °C, while moderate wind speeds enhance mixing and limit surface warming. Ensemble spreads in GFS and ECMWF runs create the tight market clustering around 17–18 °C, with differences hinging on exact cloud cover and any urban heat-island boost at official stations; clearer skies or lighter winds could push the peak toward 19 °C, whereas increased low-level stratus would favor 15–16 °C.