**Persistent humid easterly flow and typical late-summer convective patterns are positioning Miami’s August 31 high near 90°F.** Official National Weather Service and WeatherBug guidance issued August 29 forecast a daytime maximum of 90°F under mostly sunny morning conditions transitioning to likely afternoon showers and thunderstorms, with heat indices reaching 105–106°F. This aligns closely with the climatological average high of 90.2°F for the date and recent observations showing daily maxima clustered in the lower-to-mid 90s amid scattered rain that often caps peaks through cloud cover and evaporative cooling. Market-implied probabilities reflect this consensus, with 90–91°F holding the largest share (46%) and adjacent bins (88–89°F and 92–93°F) capturing the remaining bulk, indicating traders see limited upside for significantly hotter or cooler outcomes. Key variables that could shift the realized high include the exact timing and coverage of convection—stronger or earlier storms would favor the lower side of the range—while suppressed rainfall and clearer skies could push readings toward 92–93°F. Updated model runs and National Hurricane Center or local NWS briefings through August 30–31 will provide the next high-resolution guidance on these factors.