Recent National Weather Service and private model guidance for Miami on September 20 points to afternoon highs in the upper 80s amid high humidity and a strong chance of showers and thunderstorms, which typically suppress peak temperatures through cloud cover and evaporative cooling. Sea-breeze convergence and the ongoing convective regime favor scattered to likely storms after midday, consistent with climatological norms for late September. Trader positioning favoring 90–91°F as the modal outcome reflects uncertainty around storm timing and coverage; lighter or delayed precipitation could allow greater insolation and push readings into the low 90s, while earlier or heavier activity would cap them nearer 86–88°F. Updated model runs and local observations over the next 48 hours will refine these probabilities.