Official observations from Brazil’s INMET network and numerical weather models confirmed a maximum of 26°C in São Paulo on August 4, aligning with the market’s 100% consensus on that outcome. Near-surface analyses showed stable subtropical high pressure suppressing convection, producing clear skies and modest daytime heating consistent with early-August climatology of 23–25°C highs. Ensemble guidance converged tightly on this value days ahead, with minimal spread in boundary-layer temperature forecasts. A realistic challenge would require an unreported station reading above 26°C or a post-event data revision from the primary reporting site, though both remain improbable given multiple cross-validated sensors and the absence of mesoscale features capable of localized spikes.