Forecast models from Brazil’s National Institute of Meteorology and major global ensembles show a maximum near 25–26 °C for São Paulo on August 14 under typical winter subsidence, limited moisture, and mostly clear to partly cloudy skies that permit moderate daytime solar heating without strong instability. Recent passage of a weak cold front has left a drier, more stable air mass in place, suppressing cloud cover and allowing temperatures to climb a few degrees above early-month values while remaining well below summer extremes. Minor differences separating the closely matched 25 °C and 26 °C outcomes hinge on exact timing of peak insolation, urban heat-island contributions at official stations, and small ensemble spreads in boundary-layer mixing; traders weigh these variables against climatological August highs of 23–25 °C when assigning probabilities.