**Persistent easterly flow and high thunderstorm probability are capping expected afternoon heating in Miami on September 17.** Official National Weather Service guidance and multiple model runs project a high in the upper 80s amid 70–90% chances of showers and thunderstorms, with east-northeast winds of 10–15 mph maintaining a stable marine layer and limiting insolation. Typical mid-September climatology supports highs near 88–90 °F under clearer conditions, but widespread cloud cover and rainfall on the 17th are expected to suppress the daily maximum by 2–4 °F relative to that baseline. Market-implied odds cluster tightly around 86–89 °F because the precise timing and coverage of convection remain the dominant uncertainty; stronger or earlier storms would favor the lower end of that range, while any delay in development could allow brief clearing and a push toward 90 °F. Updated model runs and NWS briefings over the next 48 hours will refine these thresholds.