Recent GFS and ensemble model runs indicate Sao Paulo highs on October 9 likely peaking near 31–32 °C under partly cloudy skies with scattered afternoon thunderstorms. Southern Hemisphere spring warming, combined with the city’s urban heat island effect, supports these values, though variable low-level moisture and convective timing could cap or briefly exceed them by a degree. Light northerly winds and surface pressures near 1015 hPa favor modest mixing, limiting extreme outliers. Traders’ close clustering around 32 °C (34.5 %) versus 33 °C (26 %) reflects this narrow forecast spread and the resolution sensitivity to whether peak readings occur before or after storm initiation. Updated model guidance and official INMET observations will refine probabilities ahead of market close.