Recent forecast models from agencies including the National Meteorological Institute indicate a daily high in São Paulo on September 28 likely falling between 31–33 °C, supported by stable high pressure, northeasterly winds, and partly cloudy skies that allow strong solar heating while limiting widespread cloud cover. Recent observations show temperatures climbing through the upper 20s amid drier conditions following an unusually wet September, with low precipitation chances reducing evaporative cooling effects. Model spreads arise mainly from variable afternoon humidity and potential isolated showers, which could cap peaks near 30 °C or permit brief spikes toward 33 °C depending on timing. Updated guidance expected from regional centers over the next 48 hours will refine these thresholds ahead of market resolution.