Official measurements from Brazilian meteorological authorities recorded a daily maximum of exactly 25°C in São Paulo on October 13, anchoring the near-certain market outcome. This value aligns with observed afternoon conditions under scattered thunderstorms and moderate northwest winds, consistent with regional model guidance showing highs in the mid-20s Celsius amid typical spring variability. Historical October averages near 31°C provide context, yet localized cloud cover and precipitation kept temperatures suppressed. Future data revisions from additional stations remain the primary uncertainty, though such adjustments rarely alter the recorded peak once initial reports are verified.