Current ensemble forecasts from GFS and similar models point to Sao Paulo overnight lows near 17–18°C on October 13, driven by persistent cloud cover, high humidity, and a passing frontal boundary that limits radiational cooling overnight. These conditions, combined with light easterly to northeasterly winds, reduce the likelihood of sharp temperature drops typical under clear skies. Market-implied odds reflect this consensus while pricing in model uncertainty and potential for localized variations in urban heat islands or brief clear periods that could push readings slightly lower. Historical October minima in the region average around 17°C, providing context for why traders assign meaningful probability to the 15–18°C range ahead of final observational data from INMET.