**Forecast models from the National Weather Service and other sources indicate Miami's overnight low on August 21 will likely fall in the upper 70s to low 80s, with trader consensus centered on the 80–83°F range due to persistent summer conditions.** High atmospheric moisture (precipitable water values near 2 inches), light south to southwest winds, and urban heat retention limit radiative cooling overnight. Scattered thunderstorms and cloud cover expected into the evening further suppress temperature drops, while the sea-breeze pattern and lack of a cooler air mass keep readings well above seasonal nighttime averages near 78°F. Model consensus shows only modest variation based on exact storm timing and sky cover, explaining why the two leading bins remain closely matched rather than one dominating. Newer high-resolution guidance and updated NWS discussions will likely refine the precise minimum as the evening approaches.