A cold front arriving overnight from the south has become the dominant driver, moderating temperatures across São Paulo on August 21 after several warmer days near 30–32 °C. Official alerts from Defesa Civil and multiple forecast models now converge on a daytime maximum near 24–25 °C under increasing cloud cover, light winds shifting southeast, and a modest chance of drizzle. This places 25 °C as the consensus outcome, with 26 °C remaining plausible if urban heat-island effects or delayed frontal passage allow a brief afternoon spike. Resolution hinges on the official INMET station reading, where small differences in peak timing or cloud timing can separate adjacent degree thresholds in this tightly bunched market.