Recent model runs from meteorological agencies highlight variable cloud cover and a weak frontal boundary approaching São Paulo, creating uncertainty in peak daytime heating for May 18. This keeps implied probabilities tightly clustered around 19–21°C, as southerly airflow may suppress temperatures below the seasonal 22°C average while partial clearing could allow brief warming. Official guidance notes low precipitation risk but emphasizes how small shifts in humidity and wind patterns can alter maximum readings by 1–2°C. Traders weigh these near-term variables against historical May baselines, with resolution hinging on final verified observations from local stations.