Official meteorological observations from Sao Paulo stations recorded a daily maximum of 22°C on September 10, 2026, driving the near-certain market consensus. Persistent cloud cover, rain showers, and moderate humidity limited solar heating during peak afternoon hours, consistent with early-spring patterns where frontal systems often suppress temperatures below the September climatological average of 23–26°C. Trader positioning reflects this verified data from authoritative sources like airport and INMET networks, with minimal uncertainty in the final tally. A realistic challenge would require substantial post-event revisions to station records or redefinition of the measurement criteria, both rare once preliminary reports stabilize.