Recent forecast model runs for São Paulo on October 13 show afternoon highs clustered between 24–28 °C amid scattered thunderstorms and variable cloud cover, producing closely matched market-implied odds. Persistent northeast to northwest flow and high humidity are limiting surface heating, while timing of convective cells—expected to develop after midday—will determine whether peaks reach the upper 20s or remain suppressed near 25 °C. Official guidance from Brazilian meteorological agencies highlights model spread in instability placement and boundary-layer moisture, creating genuine uncertainty that keeps 25 °C, 26 °C, 28 °C, and 24 °C as the most probable outcomes. Updated radar and short-range model runs expected overnight will likely narrow the distribution ahead of market resolution.