Recent model consensus points to a cold front advancing from southern Brazil, advecting cooler polar air and triggering widespread thunderstorms over São Paulo on September 1. This system follows unusually warm late-August conditions, with daytime highs exceeding 30 °C, setting up a sharp temperature drop as northwest winds shift southerly. Official forecasts from sources such as the Met Office and regional models converge on a minimum near 13–14 °C overnight, driven by enhanced radiative cooling under cloudy, moist conditions and light precipitation. Trader sentiment remains closely balanced because small differences in front timing, cloud cover, or wind strength could keep the low above 15 °C or push it lower, while an unexpected delay in the frontal passage would favor warmer minima closer to seasonal norms of 12–15 °C. Updated runs from global ensembles over the next 48 hours will refine these thresholds ahead of market resolution.