Recent meteorological forecasts for São Paulo on October 7 point to an overnight minimum near 18°C, driven by persistent cloud cover, light variable winds, and elevated humidity that limit radiational cooling under springtime conditions in the Southern Hemisphere. International models and INMET guidance show consensus around this range, with minor differences in predicted dew points, frontal passage timing, or brief clearing episodes able to shift the exact low by 1–2°C. Trader-implied probabilities cluster tightly between 17°C and 19°C because these subtle atmospheric variables create genuine forecast uncertainty, while extremes below 14°C or above 21°C remain low-probability outliers given current observations and seasonal baselines. Updated model runs tonight could refine the outcome.