Trader consensus on Polymarket prices a 40.5% implied probability for a 27°C high in São Paulo today, edging out 26°C at 31.5%, amid official INMET forecast of 28°C under overcast conditions with weak southeast winds and humidity dropping to 30%. This tight race stems from discrepancies across numerical models like GFS and ECMWF ensembles, which show a 26–28°C spread due to variable afternoon cloud cover reducing solar insolation and strengthening sea breeze effects that often cap urban peaks below airport readings. Current midday observations near 24°C track slightly under earlier projections, with no major synoptic shifts in the high-pressure ridge over Southeast Brazil in the past 48 hours; hourly updates from INMET stations through late afternoon will likely resolve the market as heating peaks.