Recent forecasts from meteorological models indicate a maximum temperature near 20°C for São Paulo on May 18, driven by typical May cooling patterns in southeastern Brazil as the austral autumn progresses. Ensemble predictions show modest diurnal warming under variable cloud cover and light easterly winds, with minimum temperatures around 14°C supporting moderate daytime peaks. Historical climatology places May averages at 21–23°C highs, but current guidance suggests slightly below-normal conditions due to transient moisture influences. Traders assign the highest implied probability to 20°C because model consensus clusters tightly there, while nearby 19°C and 21°C outcomes reflect remaining uncertainty in exact timing of any frontal passages or insolation variations before the market resolves.