**Persistent afternoon thunderstorm activity and high humidity are the dominant factors capping Miami's peak temperatures on August 31, aligning trader sentiment with the 90–91°F bin (45.5% implied probability) as the modal outcome.** National Weather Service and other model guidance issued August 29 project a high near 89–90°F under mostly sunny morning conditions transitioning to showers and thunderstorms likely by afternoon, with easterly winds of 5–10 mph and heat indices exceeding 105°F. This convective regime, typical for late-summer South Florida, introduces cloud cover and evaporative cooling that frequently prevents readings from exceeding the lower 90s. Historical late-August averages hover around 90°F, but the current moisture-laden pattern and lack of strong subsidence favor moderation rather than extreme heat. Recent developments show no significant model shifts toward drier, hotter conditions that would push probabilities toward 92–93°F or higher bins. The 88–89°F outcome retains meaningful support (18.5%) if storms develop earlier or more intensely than currently anticipated. Market-implied odds reflect traders weighting these short-term NWS/NOAA forecasts and typical diurnal thunderstorm timing against the possibility of partial clearing allowing brief spikes into the low 90s. New model runs and local observations over the next 48 hours will refine the exact maximum.