Recent official observations from São Paulo weather stations indicate a nighttime minimum of approximately 17–18°C on October 13, 2026, under persistent cloud cover, light rain, and high humidity that limited radiative cooling. These conditions, combined with the urban heat island effect and mild southwesterly flow, prevented deeper drops typical of clear-sky nights in spring. Forecast models converged on similar values but diverged slightly on exact timing of the low and micro-scale variations across the metro area, sustaining tight market-implied odds between 16°C and 18°C. Updated station data and any final INMET or Climatempo verification reports expected in the coming days will resolve the precise threshold.